For all of you fantasy baseball fans, I'm sure I don't need to tell you what pyrite is.  Oh, you're not all geologists?  Well then, pyrite or iron pyrite, better known as "fool's gold," is a shiny, metallic mineral that bears a striking resemblance to the king of all metals, gold.  It's name comes from the Greek word for "in fire."  Right now you are wondering what this has to do with fantasy baseball.  We're almost there.  See, the tricky thing about pyrite is that it can be found in rock formations containing real gold, making it hard for miners to determine which is which.  We encounter this same problem in evaluating baseball players and determining if their hot streak is sustainable.  I could have simply given this recurring post a name like "Buy or Sell?", but that lacked character, so I am going with "Gold or Pyrite?"  Here, I will attempt to sort out the gold and pyrite of the fantasy baseball universe.


I will focus on players that are on a short term hot streak that are popular waiver wire pick-ups and try to advise you whether they are here to stay and the peripheral stats back up their performance (gold) or if they are a flash in the pan and will slump their way back to irrelevance (pyrite).  Let's kick this off with a quick look at ESPN's player rater for the last 15 days and see which hitters and pitchers are near the top unexpectedly.

Well, we have J.D. Martinez (3), Jake Arrieta (6), Todd Frazier (10), Steve Pearce (12), Kole Calhoun (16), James Jones (18), Jesse Hahn (21), and Mike Leake (36).  I skipped over some interesting hitters between Hahn and Leake because I wanted to include at least a few hurlers.  Now, if you don't care about why I think each of these players is gold or pyrite, you can scroll to the bottom of your screen and take a look at the handy table I have made to see the verdict for each player.  But, I suggest you read on so you can understand why I think the way I do and make a more nuanced decision with your roster.  One final note: this was written prior to the 4th of July, so the cited stats will not include the last 4-5 days.


J.D. Martinez, OF DET


He has been the talk of the fantasy community for weeks now since Torii Hunter's injury opened up playing time for him.  In the last 15 days, he has 6 HR, 16 RBI, with a .417 OBP and .818 Slugging!  Obviously, he is on a tear and he has been snatched up in 96.4% of ESPN leagues, so he is probably not available.  But, if you have him or want to trade for him, you want to know if this is for real.

Martinez was once a top prospect with the Astros, but struggled in three MLB seasons with them before being released in March of this year.  The Tigers signed him as a bench bat/backup OF.  Here is his best stat line from his time in Houston: .274/.319/.423 with 6 HR, 29 runs, and 35 RBI in 53 games in 2011, his rookie year.  Extrapolate out those to a full season and you would get 18 HR, 87 runs, and 105 RBI.  Not a bad start, but then he never hit more than 11 HR in a season and his average and OBP faltered to the point where he was released.

According to reports, over the offseason this year, he worked on changing his entire swing mechanics to become a different player.  At first glance, it appears the changes he made are working: .312/.351/.603 in 43 games with 9 HR, 18 runs, and 32 RBI.  However, what you see is somewhat of a mirage.  He has a below average walk rate at 6.5%, a high strikeout rate at 25.3%, a career high BABIP of .365 which is likely to regress back to career norms in the .320 range, and a HR/FB ratio of 21.4% (league average is around 10%).  I think the swing changes have helped, but I don't believe he will continue his current success.  I expect something like his ZiPS projection for the rest of the season: .271/.317/.428 with only 7 more HR and 34 more RBI, with the HR the most likely to be exceeded.  In other words, he is pyrite and I would be looking to sell him high.  I didn't even mention his playing time issues with Rajai Davis, Torii Hunter, and Austin Jackson all vying for time in the crowded Detroit outfield with Martinez.  The homers will likely fall off, the balls will get caught more, and the average will fall.

One final note: Dave Cameron and others over at Fangraphs have said that Martinez may be doing what Marlon Byrd did last year and selling out for power and swinging at every pitch as hard as he can.  If that is the case, the power is somewhat real and he may end up with 20-25 HR by the end of the year but the average and OBP will eventually suffer.

Jake Arrieta, SP CHC


This one-time prospect also struggled in his first four years in the big leagues.  Also like Martinez, he made some changes this year to change his fate.  Here are the ERAs he had the last four years: 4.66, 5.05, 6.20, and 4.78.  This year, it's down to 1.81.  That is backed up by a 1.95 FIP and a 2.48 xFIP, so there isn't much luck involved.  He has started throwing more breaking balls and is walking significantly fewer batters.  He has a 29% K% and a 6.2 BB%, both of which are significantly better than average.  He is throwing his slider more than any other pitch, which is normally reserved for relievers like Sergio Romo, not starters.  He uses that slider most, then his sinker, four-seam fastball, and a curve.  The curveball gets above average groundballs at 71.4%, the slider gets above average swinging strikes (whiffs) along with the curve.

Combine all this together along with the fact that he can command all of his pitches well, and you get some gold, baby!  Pick him up, trade for him, hold him, do whatever it takes to have him on your roster!  This is a legitimate improvement and I expect him to continue to pitch very well, although his current pace is Kershaw-like, so there will probably be some regression, just not too much.  The only other caveat is that throwing the slider so much increases your injury risk noticeably, so there is that.  Eno Sarris at Fangraphs says that his chances of a DL stint increase by about 4-8% with the high slider use.

 

Todd Frazier, 3B CIN


Frazier has had an up-and-down career so far.  He had a very good year in 2012, slashing .273/.331/.498 with 19 HR, 55 R, and 67 RBI.  He hit 19 HR again in 2013, but it took him 150 games instead of 128 to get there and he slashed .234/.314/.407.  This year, he's doing even better than 2012 with a slash line of .287/.354/.503 and 17(!) HR already.

Has anything changed?  Well, Fangraphs had an article about Frazier's improvement and cited his improved patience at the plate and being more selective about what pitches he swings at and this is backed up with a reduction in is out-of-zone swing percentage.  But, his .322 BABIP is in line with his career norms, so it's probably not luck.  His HR/FB ratio is a little high at 17.9%, so there will likely be some regression in the power department.  His 13 steals are a huge surprise and I wouldn't count on that pace continuing at all.  He has had no more than 6 steals in any MLB season, so he may only have a handful the rest of the year.  His walk and strikeout rates are the same as last year, but both were slightly above average last year too, so that's not a bad thing.   In the end, Frazier is gold and a clear top 10 3B in this year of poor 3B options.  This performance is mostly real and you should want Frazier on your roster.

 

Steve Pearce, 1B/OF BAL


Where did this guy come from?  Pearce has been a part time player for most of his 7 year MLB career.  He is 31 years old and has never displayed this kind of power in the majors before.  His HR/FB ratio is almost double his career high at 18.9%, so that will likely come down.  His line drive rate is up 6% from last year, which contributes to his .368 BABIP, making it not just luck (line drives have a BABIP of over .600).  His K% and BB% are both near the averages, but have declined some since last year.  He has had a pretty pronounced platoon split throughout his career with .050 drops in OBP and AVG against right-handed pitching and a .100 drop in slugging.  He is currently playing against both righties and lefties and is hitting them both well this year.

Is this for real?  Unfortunately, Pearce has not shown anything in his history to indicate that any of this is sustainable.  There have been no indications of swing changes or changes in approach.  I think this is a classic hot streak that will come to an end.  It is very rare for a 31-year-old journeyman to suddenly hit better than he ever has.  This is pyrite, folks.  I would be looking to sell Pearce now.  If you can't find a buyer, just ride out the streak with him on your roster, but be ready to let him go when the inevitable fall hits.  He may even end up on the wrong side of a platoon, hitting only against lefties, making him useless in most leagues.

Kole Calhoun OF LAA


Now, our first guy that was at least on people's radars coming into the year as a potential breakout candidate.  He has missed some time to injury this year but has put up 8 HR, 38R, 21 RBI and a .284/.345/.494 slash line in 49 games.  Those stats are almost identical to what he put up in 58 games last year, with a slight uptick in slugging and runs.  His run increase this year is almost entirely because he is now hitting leadoff ahead of a few guys you may have heard of named Trout, Pujols, and Hamilton.  Nothing in his profile suggests that this is unsustainable and his BABIP and HR/FB ratio are both in line with career norms.  Here are the only problems with Calhoun that keep him from truly breaking out: he cannot hit lefties and the Angels sit him against pretty much all of them, his infield fly ball % and ground ball % are up a couple % from last year, and his line drive % is down 3%.  None of those things are deal breakers, but in weekly leagues, you will have to bench him during weeks where the Angels face multiple lefties.  The batted ball % changes are worrying only if they continue to get worse.

Watch those trends as the season goes on to see if it might be time to trade him or let him go.  In the meantime, Calhoun is gold!  Hold him or trade for him, especially if you are in a daily league, where his platoonage is not a problem.

James Jones OF SEA


No, you didn't stumble into a fantasy football post by accident.  This is not the 49ers wideout.  This is the Mariners outfielder and speedster.  This 25 year-old has done well in his first action in MLB.  He has a .293/.322/.361 line with 34 runs and 17 steals in 57 games.  The speed is legit, he has stolen over 20 bags in every full minor league season.  The power is also legit, in that he doesn't have it.  He is not going to help you in slugging, HR, or RBI at all.  He doesn't walk much with only a 4.1% walk rate, well below average.  His BABIP is a little high at .355, but he is fast so that isn't unreasonable, especially compared with his minor league numbers.  He has shown a below average K%, which helps keep his average high and has had above average walk rates at every minor league level, so his walks could definitely improve.

Where does this leave us?  I think Jones is gold, Jerry, it's gold! (Seinfeld reference).  He is basically as advertised: no power, decent number of runs, good steals, good batting average, average OBP.  If that is something you need in your 4th or 5th outfield spot, you could do much worse than Jones.  Plus, he is hitting leadoff or second in the lineup, so the runs should continue to happen, especially as Cano returns to being who we expect him to be.


Jesse Hahn SP SD


Another rookie (only our second on this list), Hahn has gotten off to an amazing start in the majors with a 1.95 ERA!  He has a 11.7 K/9, 3.25 BB/9, a 2.74 FIP, and a 2.59 xFIP.  These are all elite numbers.  Now, he is not David Price or King Felix, so these numbers are going to regress.  We know this.  But how much?  Well, his K%-BB% is in the elite pitcher range in the small sample of 27 innings this year. He did not show the strikeout ability at all in the minors, with 7.75 K/9 in AA earlier this year, and similar rates in the lower minors.  The data is telling us he is playing way over his head compared to his past history and the projection systems predict 6.4 or 8.3 K/9 with ERAs of 4.24 or 3.99 for the rest of the year (ZiPS and Steamer).

How do we know if this is legit?  Well, the K%-BB% has been shown to be the best in-season predictor of future performance, according to Fangraphs.  So he's got that going for him.  Next, I look at this pitch mix.  He is throwing mostly a 91 MPH fastball, a 74 MPH slow curve, and a 90 MPH two-seam fastball.  He throws the fastball or curve 84% of the time, making him almost a two-pitch pitcher, which is worrisome.  He does have a change up that he throws about 3% of the time.  Next, I look at his swinging strike rates on his pitches.  His four-seam fastball has a league-average whiff rate, his curve ball is way above average, along with his two-seam fastball.  The change-up is about average as well.  That is a pretty good arsenal.  Both of his fastballs get above average ground ball rates as well.  Put all this together and you get gold.

Hahn is for real, and while his ERA will probably end up in the 3.2-3.5 range instead of 2.00, he should continue to have success and rack up strikeouts.  His control has always been good, so that should help too.  The great home ballpark is also a huge help for those home starts.  I would look to acquire Mr. Hahn immediately or pick him up if he is available for some reason.

Mike Leake SP CIN


The last guy on our list is Mr. Leake.  He has had an up and down career like his teammate Frazier.  His ERA has bounced: 4.23, 3.86, 4.58, 3.37, and now 3.47.  That's two straight years of above average ERA.  This year, his FIP is at a career low 3.66.  His overall ground ball rate is at a career high, along with his strikeout rate.  Don't get too excited about that K rate, it is still only about 7 K/9.  His slider does get fantastic swinging strike rates and his cutter is above average.  His four other pitches, yes he has six pitches, are below average for strikeouts.  His sinker, cutter, curve, fastball, and change all get good ground ball rates, though.  His walk rate has always been elite, but now his strikeout rate and ground ball rates are adding to his arsenal.  His xFIP is a nice 3.32, indicating he has been a little bit unlucky this year.  I have long been a disbeliever in Leake due to his low K-rate, but he has changed my mind.  Leake, you are golden.

Like Hahn, there really isn't a good story behind his improvement; no new pitch or mechanics adjustment, just overall improvement.  He is throwing his very good slider more this year and he is throwing his sinker more and his fastball velocity has unexpectedly increased almost every year of his career: 88.5, 88.2, 89.4, 90.1, 90.7 MPH.  That is the opposite of the typical aging curve.  This small uptick in velocity certainly could be helping his numbers.  His swinging strike rates are up on almost all his pitches this year as well.  You should be buying Leake.

The Gold or Pyrite? Table At the End of the Post for Quick Reading!

J.D. Martinez = Pyrite
Jake Arrieta = Gold
Todd Frazier = Gold
Steve Pearce = Pyrite
Kole Calhoun = Gold
James Jones = Gold
Jesse Hahn = Gold
Mike Leake = Bronze, just kidding, he's Gold

There you have it!  I guess we found out that most of these guys are legit, so happy trading!  Let's do this again sometime.  We'll check back in a few weeks to see what new players are topping the ESPN 15-day player rater and play America's new favorite game: Gold or Pyrite?  Tschuss!

I'm still just dipping my toes into the Twitter waters, so I'm not yet active there, but you can find me on the fantasy baseball subreddit as WisconsinsWestCoast.  Feel free to DM me your fantasy questions.