CLEVELAND -- Rain showers had washed away Triple-A Columbus' pregame plan, and Corey Kluber retreated to the confines of a cage to complete his workout. With rain falling and nothing but time on his hands, the pitcher decided to have some fun with the mound session.
Kluber fired his customary four-seam fastball, but he then started working in a two-seam sinker every few pitches. Ruben Niebla, who was Columbus' pitching coach during that 2011 season, liked what he saw and told the right-hander to finish the workout with nothing but sinkers.
"I'd never really thrown it much on a consistent basis," Kluber said. "I'd throw my four-seam and, here and there, I'd mix in a two-seam. After I threw it over and over and over and over, and it kind of clicked. It was like, 'This feels a lot better.'"
What the Indians could not have known on that rainy afternoon three years ago was the turning point in Kluber's career had quietly arrived. There, in that batting cage, Kluber found a fastball that he would learn to manipulate and command with pinpoint precision, opening the door for his other offerings to be more effective.
Heading into Monday's off-day for the Tribe, Kluber was 13-6 with a 2.46 ERA and a 1.07 WHIP through 25 starts this season, one that's catapulted him to the top of the American League's pitching ranks. Kluber began his ascension in Cleveland's rotation last season, but he has rapidly developed into the unquestioned leader and future ace for a staff otherwise in flux.
What is the feeling like for the Indians when Kluber takes the mound?
"He's getting an air about him like a Nolan Ryan or a Roger Clemens," pitching coach Mickey Callaway said without an ounce of exaggeration. "That's what I feel like when he's on the mound. I feel like one of those guys is pitching right now."
The first thing that stood out to Kluber when he began to work exclusively on his sinker was the feeling of the baseball in his grip. The righty prefers to have the ball farther back in his hand, whereas other pitchers might position it more toward the fingers.
"He likes to feel those seams on his fingers," Callaway explained. "Every grip he has is kind of deep in his hand. He doesn't grip the ball out on his fingertips. So I think those two-seams, really feeling it on his fingers helped out."
A traditional sinker will dive down and away from a left-handed batter, or low and inside on a righty. Kluber's acts slightly different, in that it has more run than sink. What that means is that while the ball tails rapidly away from a lefty or in on a righty, it does not drastically fall down through the zone.
A good example of how Kluber uses his sinker to induce weak contact came in the first inning of Saturday's win over the Yankees. Facing veteran shortstop Derek Jeter, Kluber fired a 93-mph two-seamer in a 1-1 count. The baseball started over the plate, but it quickly tailed in on Jeter's hands, inducing a chopper back to the mound for an easy out.
According to brooksbaseball.net, which compiles PITCHf/x data from every Major League game, Kluber has thrown his two-seamer 49.7 percent of the time this season. The starter features the pitch nearly the same amount against lefties (48.9 percent) and righties (50.3 percent), using it as a way to get ahead in the count and tempt hitters to swing early.
Kluber has read "The Mental ABCs of Pitching" by H.A. Dorfman multiple times -- a book famously known to be a favorite of former Major League ace Roy Halladay -- and he has embraced many of the core principles. Kluber never studied Halladay's approach specifically, but he said the book has led him to use similar techniques.
"I know the author worked with Halladay a lot," Kluber said. "Maybe coincidentally, through that process, some of that same stuff -- as far as attacking the zone, attacking hitters, trying to get early contact -- kind of molded me into the same approach."
Kluber does not always use the two-seamer to create contact, though. While that is the primary purpose of the pitch, the right-hander has chalked up 42 of his 187 strikeouts to date this season with the sinker. It's not his main put-away pitch, but when featured at the right moment, Kluber can get swings and misses.
In the sixth inning on Saturday, New York's Stephen Drew watched a 1-1 sinker tail into the zone for a called strike. One offering later, Kluber came back with a 94-mph two-seamer that missed Drew's bat for an inning-ending strikeout.
During his early Minor League days, Kluber essentially featured a curveball and a changeup to offset his inconsistent four-seam fastball. With the addition of the two-seamer, and a cutter that Kluber has honed over the past four seasons, the changeup arrives occasionally, but it's nearly nonexistent.
Callaway says the two-seamer has increased the effectiveness of Kluber's two main offspeed offerings.
"We always knew that he had the great offspeed pitches, that he could spin the ball," said Callaway, who worked as a Minor League pitching coach prior to taking on the Major League role last season. "The problem before was, hitters could say, 'OK, I'm going to wait for the cutter. I don't have to respect the fastball, because he's not throwing it over.'"
With that old troublesome four-seamer now sent to Kluber's back pocket (he has thrown it only 2.6 percent of the time this season), hitters can no longer sit on the pitcher's cutter. While the two-seamer runs away from a lefty at around 93-95 mph, the cutter breaks down and in at a slightly lower velocity (89.8 mph on average).
Kluber has used the cutter 27.2 percent of the time this season, which is roughly the same usage as in his previous Major League seasons. The pitcher said the biggest difference now with that offering is he can throw it to specific spots with conviction.
"Starting off, it was a pitch where I just threw it in the vicinity of the plate and hoped it would work out," Kluber said. "It wasn't something that I was comfortable enough with to put in a certain spot. Now, I feel like I'm to the point where I can locate it to both sides of the plate and move it up or down."
Entering Monday's action, Fangraphs.com gave Kluber's cutter a 12.2 rating, which was the second-best cut fastball in baseball behind Cardinals ace Adam Wainwright (16.9). Yanks outfielder Jacoby Ellsbury saw how valuable the pitch was in the first inning on Saturday, when he checked his swing too far on an 89-mph cutter that broke down at the last moment.
Kluber's curveball has similar action as his cutter, but it arrives to the plate at 83.3 mph on average. Hitters who commit to a swing at a cut fastball will find themselves out on their front foot as the slider drops below their barrel. The pitch has similar action to a slider, but it's classified as a curve when it comes to PITCHf/x data.
This season, hitters have posted a .072 (11-for-153) average in at-bats ending with Kluber's curveball, which has Fangraph's highest rating (17.7) in the Majors for that particular pitch. Lefties (.076 average) and righties (.068 average) have been equally victimized by Kluber's breaking ball this year.
In the sixth inning of Saturday's game in the Bronx, Yankees first baseman Chase Headley flailed at an 84-mph curve from Kluber for one of Kluber's 10 strikeouts that afternoon.
Kluber said the development of his two-seamer and cutter -- both added in 2011, when the righty was also undertaking delivery changes -- have been critical to his success with the Tribe. Adding the cutter is what gave him a three-tiered approach in terms of velocity.
"I have a little closer to three speeds with pitches, instead of just either hard or soft," Kluber said. "I think for almost every pitcher, the fastball is the most important. Fastball command for 99 percent of guys is going to be what separates a good day from a bad day."
And what if it had not rained on that afternoon three years ago?
"I guess we'll never know," Kluber said with a smile.
Jordan Bastian is a reporter for MLB.com. Read his blog, Major League Bastian, and follow him on Twitter @MLBastian.