Chris Tillman talk: Why did he struggle in 2015?

Here is a good question: Why did Chris Tillman struggle so much during a 2015 season where he went 11-11 with an ERA of 4.99?

Those that feel Tillman simply regressed to the mean must not have been watching from 2012-14. In those three years, Tillman went a combined 38-16 with an ERA of 3.42. In those years, he ranked tied for 11th in the American League in wins and was 15th in ERA.

No, he is not an ace pitcher, nor was he then. But he was the Orioles' No. 1 and pitched like a top-of-the-rotation starter for most of that three-season stretch. And then last season, he didn't pitch like that. Maybe for a few starts he did, but not for much beyond that.

This was Tillman's worst season since he went 3-5 with a 5.52 ERA in 13 starts during a 2011 season when he was still riding the Norfolk-Baltimore shuttle.

From 2012-14, the Orioles went 55-27 (.671) in Tillman's 82 starts. This year, they went 15-16. They went from winning two of every three to less than half.

There were a few areas on the stat sheet that were quite different for Tillman in 2015 than in 2014. One area was in his pitching against right-handed batters:

Against right-handed batters in 2014: .225 average, .385 slugging, .672 OPS
Against right-handed batters in 2015: .271 average, .500 slugging, .828 OPS

Perhaps a combination of fastball command that was not as solid in 2015 and an inconsistent curveball were factors against right-handed batters. According to FanGraphs, Tillman threw a lower percentage of curveballs this year at 14.2 percent than he had from 2012 to 2014, when those numbers were 17.4 percent, 17.1 percent and 17.6 percent.

Tillman also struggled more to get the leadoff batter out in an inning and to strand runners in 2015. In 2014, leadoff batters hit .232 against him and that went up to .302 in 2015. In 2014, he stranded 76.7 percent and that went down to 68.2. Also, the batting average on balls in play against him went up from .267 to .293.

All of these numbers provide at least some explanation why Tillman's ERA rose so significantly. Now the question is: Will he look more like the 2012-14 Tillman next year or the 2015 version?

I would think we have enough evidence from 82 starts over the three previous seasons to make Tillman's 31 starts this past year look like the outlier.

Will Tillman bounce back to his previous form in 2016?