Five Surprises Among the Last 30 Days’ Best xFIPs

A pitcher’s excellent performance early in the season can obscure poor performance later on, as his stats slowly converge toward expectations. If you held onto Jordan Zimmermann too long, you suffered the consequences. The same applies for the opposite scenario; Matt Shoemaker has been one of the baseball’s better pitchers since mid-May after an atrocious start to the season.

Alas, the deeper we get into the season, the more important it becomes to check recent leaderboards. With the way player performance ebbs and flows during a season, a span of five or six starts can probably be considered a small sample size. Still, keeping an eye on these small samples can illuminate interesting trends.

For whatever reason, there seem to be a lot of unfamiliar or unexpected names on FanGraphs’ xFIP leaderboards under the “last 30 days” split. Let’s break them down!

(All statistics as of Saturday, July 10.)

5. Bud Norris, LAD

Some criticism surrounded the Dodgers’ decision to acquire Norris. Given his mostly lackluster career, it seems like a weak move, on paper, to bolster a Los Angeles rotation that has disintegrated before our eyes.

Except Norris posted a 2.35 xFIP in the four starts before the Dodgers nabbed him, striking out almost 10 hitters per nine innings, walking only 1.5 per nine, and inducing ground balls at a 56.7% clip. Since June 10, his 2.78 xFIP and whopping 10.2 K/9 have propelled Norris to the 5th-best xFIP — and the most WAR (1.4) — in the last 30 days.

Norris hasn’t altered his repertoire, but he has changed how he utilizes it, steering away from his sinker and fastball in favor of his slider and cutter. The results have been staggering, mostly because the latter two pitches have been far more effective in terms of inducing whiffs and ground balls. It’s simply an instance of pitch optimization, much like Shoemaker’s decision to begin to rely heavily on his splitter.

As long as Norris continues to rely on his best pitches, there’s no reason to think he can’t sustain his increased rate of swings on pitches outside the zone and swinging strike rate. The league may catch up to him a bit, but I think Norris has established a new baseline. If he’s still available in your league, you should make room for him on your roster now.

10. Tyler Anderson, COL

It’s not like I didn’t know who Anderson was, given he was once a first-round draft pick. But I legitimately had no idea he was up at the Major League level after missing the entire 2015 season and seeing scarcely any time in the Minor Leagues during his comeback. Thus, seeing his name on this list was especially surprising to me.

Based on limited knowledge of his offerings this season, he’s throwing a change-up (which was his bread-and-butter pitch during his days as a prospect) that lives at the extremes: it has induced whiffs on more than a third of swings, but it also allows an elevated (no pun intended) fly ball rate with a few too many home runs to boot. The cutter has actually been more effective, inducing ground balls almost 70%(!!!) of the time while inducing a fair number of whiffs. At this point, though, it’s only his third pitch.

Really, Anderson’s biggest concern is the fact that half his starts will take place at Coors Field. But let’s keep this in perspective: if the season ended today, Anderson would post the highest single-season ground ball rate of any Rockies pitcher since Baseball Info Solutions (BIS) began tracking data in 2002. Among the 10 best single-season ground ball rates, only one pitcher — peak Ubaldo Jimenez, in 2009 — posted a strikeout rate better than 8 K/9.

Frankly, if Anderson sustained this performance, he could end up being one of the best Rockies pitchers in recent memory. That’s not to say he should be valued as such — it’s barely 36 innings, after all. But if there’s any below-the-radar name to keep track of, it should be Anderson.

11. Luis Perdomo, SDP

To establish some context: prior to this season, Perdomo had never pitched above High-A ball, and he wasn’t doing anything special, either. San Diego is not flush with talent the way St. Louis is, though; the Padres needed Perdomo, and somehow, he has answered their call. And, somehow, he has thrown better as a starter than he did in relief to begin the season.

You probably don’t care about Perdomo, though, because his 4.93 ERA in the last 30 days likely scared you away. A .368 batting average on balls in play (BABIP) and 22.2% HR/FB rate surely didn’t help. In terms of peripherals, though, more than eight strikeouts and fewer than three walks per nine innings will do the job, especially with a 67.2% ground ball rate.

A lot of times, I’ll look at a pitcher’s zone contact rate (Z-Contact%) to see if he’s getting a little lucky with strikeouts. Baseball’s elite pitchers will post rates in the low-80s (or even high-70s) in terms of percentage; baseball’s least effective may post rates in the low-90s. With that said, Perdomo is below-average in this regard. It’s his ability to limit contact on pitches outside the zone (O-Contact%) that has propelled him to (peripheral) success.

It’s hard to believe that he’ll sustain his remarkable xFIP simply because of his story. He’s still young — only 23 — but he was acquired by Colorado as a Rule-Fiver before being acquired by the Padres and was very old for his level of play. (He’s not anymore, obviously.) Chris Mitchell’s KATOH projected a low upside for Perdomo but acknowledged that the Toronto Blue Jays’ Roberto Osuna made the jump directly from Single-A and succeeded almost immediately. Perdomo has that opportunity, but it’s weird to see a less-hyped arm succeeding in a more taxing role.

I guess I used a bunch of words to give you a very fuzzy evaluation. Truth is, I don’t know what to expect. Perdomo’s results haven’t matched his performance, so it’s likely that very few of you are invested in his success at this point. It’s possible, though, that Perdomo puts together a nice run soon, and we all start to take notice. Or, he regresses to something more typical of his skill set. It’s hard to say. I wouldn’t rush to add him, but he’s worth keeping an eye on in deeper formats.

17. Robbie Ray, ARI

Ray has gotten very little attention despite doing one thing really well: striking out hitters. His 10.63 K/9 ranks 8th among all qualified pitchers. In fact, he and Drew Pomeranz have been almost identical pitchers this year outside of contact management:

More granular batted ball data tells us that Pomeranz’s and Ray’s nearly identical xFIPs are not created equal. Pomeranz is the superior pitcher here, despite Ray’s preferable strikeout skills, because of Pomeranz’s ability to limit hard (and induce soft) contact. Still, few pitches post BABIPs in the .360s over the course of a full season, so one can reason that Ray has been quite unlucky in terms of batted balls this year.

That makes Ray an interesting pitcher both now and moving forward. He could become an absolute force through August and September if he benefits from regression. And if he improves his contact management skills, he could be a legitimate mixed-league option in 2017. Until then, we keep dreaming. Ray is worth owning in deeper formats and makes for a boom-or-bust streamer in standard and daily formats depending on the opposition.

19. Chad Bettis, COL

Two! Two Rockies on this list! What an accomplishment.

Bettis has been a serviceable starting pitcher for a year or two now, having generated almost 2 WAR in a mere 115 inning last year. He has sacrificed strikeouts for command, ramping up his first-pitch strike rate (F-Strike%) to 65.5% and pounding the zone more often. Per xFIP, it has been an equal trade — his 3.95 xFIP this year almost perfectly replicates his 3.89 xFIP last year.

With that said, Bettis is nothing special, and his recent decent stretch has been dampened by an unforgiving .386 BABIP. Like Perdomo, he probably hasn’t been on your radar, and as a pitcher for the Rockies, he will likely remain off of it. He’s a worthy consideration in deeper leagues, though, as his skill set — moderate strikeouts with very few walks — has proven effective time and again by the likes of Josh Tomlin, Bartolo Colon, et al. Those kinds of guys are never elite, but they get the job done.

An aside: between Anderson, Bettis, Jon Gray and Tyler Chatwood, the Rockies could finish the season with four starting pitchers with above-average ground ball and strikeout rates. In the last 30 days, Rockies starters have posted the 8th-best xFIP and 7th-best WAR. I’m guessing that’s something we didn’t expect to say at any point this year, and it’s half the reason they pretended to be contenders as long as they did this season. With the right offseason moves, the 2017 season could be an interesting one in Colorado.