That's no longer a problem, and Butler, 24, aims to demonstrate his full arsenal against the Brewers.
"All through the Minor Leagues, that's how I felt about my sinker: I could throw it any time to anybody and know they're going to hit a weak ground ball, break the bat, swing through it; that it was going to be tough for them to square it up," said Butler, the Rockies' No. 2 prospect. "It's the kind of stuff I'm able to do. I could tell some guys it's coming and they still won't hit it far. Last year was tough; that part shook me a little bit."
A healthy Butler with a better plan for shoulder maintenance and more strength in his lower body now believes he has his best sinker. Against Major League hitters, he can't overthrow the pitch. But when it's the right velocity and the right sink, he believes he can do the same to the sport's best hitters that he did to developing guys in Double-A and below.
"I think I'm better, stronger and I can throw it more often without having to try to overthrow it," Butler said. "Before, I'd overthrow and give up jam shots, but they were getting it over the infield because the ball was elevated."
There will be some learning for Butler, but the sinker -- coupled with a 96-mph rising fastball he throws to keep hitters from thinking low -- can cover for a lack of experience.
"He's got stuff that can get through Major League lineups, and that's a nice luxury to have," Rockies manager Walt Weiss said.
• Catcher Nick Hundley's pitch-calling strategy was part of the reason for Kyle Kendrick's seven scoreless innings in Monday's 10-0 victory over the Brewers. But Michael McKenry also gets high marks for being able to help a pitcher through games.
Weiss is comfortable with either, even when the pitcher is a young arm like Butler.
"You want a guy back there, especially with the young guys, that can get them through those tough spots," Weiss said. "We've got a couple of guys that can do it; and [Wilin] Rosario, when he's back there, has got a lot of history with those guys."
Weiss said he is not planning to give a pitcher a so-called "personal catcher," because there are other factors that go into putting together a lineup.