"When I got here to Arizona, sat with the training staff and went over how things were going, they checked me out and said my body was fatigued," Butler said. "They said it would be a better idea for me to stay here and get stronger, rather than go pitch.
Butler missed time midseason because of a strained right rotator cuff, which showed up after his Major League debut on June 6. Butler rehabbed, then finished the season at Double-A Tulsa before returning to the Majors for two late-season starts -- a six-inning, one-run effort in a win over the D-backs on Sept. 20, and a 4 2/3-inning struggle in a loss to the Dodgers on Sept. 27.
After his final start, Butler reported unusual soreness in his upper back/shoulder area. The Rockies made the decision several days ago to remove him from the AFL club. It came to light Tuesday, the first day of scheduled games.
Butler said he visited with club physicians, who assured him that the upper-back pain was muscle fatigue that could be corrected with rest and rehab, and not a significant injury.
A supplemental first-round pick in '12, Butler became a top prospect in '13 when he displayed a 95-mph fastball and struck out 143 in 149 2/3 innings. He showed some of that fastball electricity during Spring Training, but during the regular season -- spent mostly at Double-A Tulsa -- his fastball velocity dipped to the low 90s and he struck out 69 in 117 1/3 Minor League innings, and three in 16 innings in the Majors.
Whether it was pain or poor mechanics, Butler felt he lost his optimal arm slot this season. The Fall League assignment was designed to give him consistent innings in hopes of regaining it. Now, Butler believes time off from pitching and his strengthening program will accomplish the same goal.
"I even talked to some scouts who saw me when I was in college," Butler said. "They mentioned things like, 'Your arm slot is not quite where it was when I scouted you a couple years ago.' I think by taking some time off and working on some physical things, it could kind of reset itself. I'll get the old muscle memory back, instead of going back to where I've been this year -- searching."
Like all teams, the Rockies want innings out of their starters. One method for pitching deep into games is forcing outs with early contact. That can be a drawback for a strikeout pitcher, since it takes at least three strikes for an out, as opposed to one on a ground ball. Although his strikeouts went down this year, Butler said he was not told to change his style or his mentality.
"It was the same mentality," Butler said. "The big difference was the maturity of the guys I was facing. In the lower levels they're much more free-swinging. Up here, they have a pitch or a location that they're looking for. It makes it tougher. Also, guys have a better two-strike approach here."
The Rockies have replaced Butler on the Salt River roster with right-hander Nelson Gonzalez, who made 47 relief appearances at Double-A Tulsa in '14 and went 6-3 with a 4.14 ERA. Gonzalez struck out 54 and walked 26 in 67 1/3 innings.