FanPost

Trevor Rosenthal, What Is He Doing

I have been wanting to write a fanpost about Rosenthal's repertoire for months now, and I've finally found a small window of time to do so. This is going to be more of a copy and pasting of charts from over at brooksbaseball.net than anything, since I don't have long to write this but wanted to see what he is doing as a pitcher in data form.

Trajectory and Movement - from 03/31/2012 to 08/26/2013

Pitch Type Count Freq Velo (mph) pfx HMov (in.) pfx VMov (in.) H. Rel (ft.) V. Rel (ft.)
Fourseam 1251 78.58% 98.23 -4.10 10.26 -0.91 6.10
Change 179 11.24% 88.81 -7.85 5.91 -0.70 6.02
Slider 42 2.64% 89.55 2.02 2.04 -0.99 6.04
Curve 120 7.54% 81.38 5.10 -5.94 -0.66 6.12

So Mr. Rosenthal has had an average fastball velocity of over 98 mph! While his changeup and slider have been under 90 mph. His curve is down towards 80 mph usually. The fourseam and the change are his main tools of devastation. This is shown in his super awesome ERA (2.49), FIP (2.20), and xFIP (2.50). This guy is just really good and has been the guy from the bullpen. Would really like to see him become a starter next year.
What I can say right now, is that I am very impressed with the Brooks Baseball player card idea and execution. It is really really cool. They have made a ton of progress over the last couple years, and I encourage everyone to use it more often. Last thing I'd like to check on is how Trevor has been seeming to be more wild lately. First off, here is the chart for his MLB career:

41.6% of his pitches are in the zone here, and 58.4% are outside the zone (and of course, batters sometimes chase these, not a reflection of his ability to throw strikes really). And this is over the last 2 months or so: Since June 26, he has definitely moved away from his career norm a bit, he's at 59.8% out of the zone. What's more alarming though is over the last month:

Over the last month he's only throwing 38% of his pitches in the zone. Well maybe I'm overreacting, but to me it shows signs of fatigue at the least. I hope he can continue to be as effective as he has been... so back to fangraphs. Rosenthal's FIP was at a respectable 3.44 in April, a lights out 0.29 in May, 2.11 in June, 1.03! in July, but in August it has been 4.00, by far the worst of the season.

I'm not sure I want to read too much into this, so VeB let me know what you think. It sure does seem he is tired this last month. There is no question he had overall a more effective first half. He seems to have the build though to be a pitcher with endurance. I'm just hoping he can be even close to as effective as he's been before August going into September and hopefully the postseason.

[disclaimer: sorry about the formatting, my html skills and whatnot are not very up to date]