I’m a long-time lurker here at Camden Chat, and figured the best way to become more involved in the community here was to write a thoughtful Fanpost– plus, I have a report due tomorrow that I’d like to procrastinate, so this seems like a good way to accomplish that. Right now a hot topic in Birdland is the state of our rotation, so this seems to be a good issue to discuss in my first Fanpost. So here we go, any feedback is welcome :)
With our rotation struggling to put in a consistent performance night in and night out (and to keep our bullpen off the field), many are calling for Chris Tillman to be demoted to Triple-A, once Brian Matusz or Alfredo Simon or whoever is able to return to the bigs. Since his first game of the season, in which his line was 6IP, 0R, 0H, 3BB, 5K, we have watched Tillman allow 22 runs over 21.2 innings, good for a 9.14 ERA over that stretch. So what’s going on with this guy, and does he deserve the criticism he’s received so far this season?
Some of Tillman’s peripheral stats actually suggest that he is pitching okay. His BABIP up to this point in the season is .361, which is far above the average, so perhaps he’s experiencing some bad luck. To confirm this we can look at his xBABIP, which comes in at .293 (Fangraphs writes that the "ballpark" calculation for xBABIP is LD% + 12%). Tillman is also pitching to the tune of a 6.18 K/9 and a 2.93 BB/9, better than Zach Britton in both categories (5.02 and 3.35, respectively, for Britton). In addition, Tillman is sporting a ridiculously low HR/FB% of 4.5%, below both the major league average and his own career average. This makes his FIP, which is based on the three preceding stats, come out to a team-best 3.48.
Judging from this, it seems like it would be a bad idea to yank Tillman from the rotation. His rate stats and advanced stats suggest that he ought to regress for the better over the course of the season. The only exception to this is his HR/FB%, which is bound to go up – but even so, his xFIP comes in at 4.36, which isn't a great number, but it isn’t bad enough to merit his demotion, in my opinion. I’m sure many will say, too, that Tillman needs to move down to work his fastball*. It is true that Tillman has lost some velocity on his fastball, but unless he’s injured, what is a trip to Norfolk going to do to fix his velocity? Jerking him back and forth last year certainly didn't help him develop.
* it would be nice to look at this Pitch/FX or another advanced tool, but I’m not knowledgeable enough to do this on my own.
All this considered, I think Tillman, who has never had a fair chance to prove himself in the bigs, ought to stick in the rotation. The O’s still have some time before they will need to bump someone from the rotation, as Matusz is still healing, Simon might end up in the bullpen again, and Duke would surprise nobody if he didn’t pitch at all this season. But when that time comes, I hope they place some faith in Tillman.