Trevor Cahill’s salient mechanical tweak

Slated as the Arizona Diamondbacks’ no. 2 starter at the season’s outset, Trevor Cahill saw his season, like his arm slot, trend downward before hitting the disabled list on July 1.

Though managing a 2.84 ERA in April and a 2.91 in May, Cahill allowed 27 earned runs in 24.2 innings pitched in June, spread over six starts, good for a 9.85 ERA in the month. Suddenly, his season’s trajectory was dipping heavily. And so, too, was his arm angle, according to Diamondbacks manager Kirk Gibson.

“He was tending to drop down too far,” said Gibson of his pitcher prior to Saturday’s game versus the San Francisco Giants, which Cahill started.

The 25-year-old Cahill was put on the 15-day disabled list with a hip injury that was suffered in a late June start. And the break couldn’t have come at a better time, given the pitcher’s struggles throughout the month.

Upon his return to the active roster on August 17, the right-hander worked with Diamondbacks coaches on a mechanical tweak — adjusting his arm slot and release point. Instead of trying to “manipulate the ball,” as Gibson would explain, by dropping his arm further down to the side, utilizing a more horizontal delivery, Cahill experimented with a higher arm slot.

In effect, the tweak accentuated his best pitch — the sinker — revealing a more drastic descent to the batter’s eye.

“He’s staying on line a little more, getting his arm a little higher instead of pulling laterally,” Gibson expounded.

(Left: Trevor Cahill pitching to Buster Posey on June 8; Right: Cahill pitching to Buster Posey on August 31)

Cahill, too, betrayed the change in his arm angle, after Saturday’s solid outing.

“I feel like it’s not dropping as low anymore,” he said. “It’s a little higher.”

And the proof is in the pudding. Cahill has a 2.08 ERA in his last three outings — including his first career relief appearance in an 18-inning marathon win against the Philadelphia Phillies — allowing four earned runs in 17.1 innings pitched. The pitcher has the sixth-best groundball rate in the majors in that span, eliciting grounders on nearly 60% of opposing hitters’ batted balls.

“When he does that,” Gibson told reporters, “(you can see) how much sink is on his ball. I mean, it goes straight down.”

Thus, the groundball spike.

The tweak has transcended immediate effectivity, helping Cahill’s confidence and command in the process.

“Just the consistency of where your arm is coming down, where you’re not chasing it all the time (makes) the delivery cleaner,” said Gibson. “It’s more consistent. When the release point is more consistent, it’s just easier to have better command.”

The manager added, “He’s just got more confidence.”