Scott Alexander threw his power sinker 91.9% of the time last year — the highest percentage among pitchers to toss at least 40 innings — and for good reason. It was an elite offering. Working out of the Kansas City bullpen, Alexander logged an MLB-best 73.8% ground-ball rate and snazzy 2.48 ERA over 58 appearances covering 69 frames.

His worm-killing weapon will be on display in a new location this coming season. In a deal examined by Travis Sawchik last night, the Los Angeles Dodgers acquired Alexander in a three-team trade that also involved the Chicago White Sox.

The 28-year-old southpaw qualifies as a late-bloomer. A sixth-round pick by the Royals in 2010 out of Sonoma State University (he was originally at Pepperdine), Alexander went into last year with just 25 big-league innings under his belt. Thanks to a velocity jump and increased usage of his sinker, however, he emerged as one of the best under-the-radar relievers in the junior circuit.

Alexander discussed the evolution of his signature pitch when the Royals visited Fenway Park last summer. Also weighing in on the southpaw’s development was Kansas City bullpen coach Doug Henry.

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Alexander on learning his sinker: “I throw a one-seam sinker. The grip was taught to me in college by Scott Erickson. I think he might have been trying to make a comeback at the time, and he’d come over to our field, at Pepperdine, to work out. I was throwing a bullpen and he saw that my ball had natural movement to it, kind of a natural tail. He asked me what I was throwing, and I showed him my grip, which was a four-seam. He showed me his one-seam grip.

“I kind of started using it, but I couldn’t really control the pitch, so I stopped. But then, when I got to Double-A in 2011, I was struggling. What I was doing probably wasn’t going to be good enough, so I decided I had to try things. When I was warming up, I’d have the catcher tell me when I threw a good one — a good sinker, a good moving fastball, whatever — and I threw a few with what had become my normal two-seam grip. Then I threw one like Erickson had shown me and the catcher was like, ‘Yeah! That’s good.’ So from that point on, I started throwing it.”

Alexander on his grip and getting ground balls: “I hold it off my middle finger, off the one seam, kind of delicately. The pressure is on the tip of my finger. I guess I kind of hold it like a two-seam, but I twist it over to where my pointer finger is… maybe it’s on the seam, but I don’t really have much going on in there; there’s not much pressure being applied. Anyway, I’m not putting any force on it. I just throw it — I throw it normal — and it kind of does what it does.

“As I’ve thrown it more, I’ve started to get a little better feel of being able to maybe make cut a little bit, or maybe add or subtract on the velo a little bit. But mostly I just try to keep it low. There are times where I’m OK with walking people, because I feel confident enough that I can get a ground ball.”

Doug Henry on Alexander’s sinker: “His ball just sinks harder than most people’s. If you watch his sinker, and watch Zach Britton’s… it ranks right up there with that one — it’s that good, and it’s hard. He’s throwing harder than he has in the past couple of years, so his sinker isn’t just biting hard, it’s coming in with really good velocity.

“If you look at the guys who had power sinkers back when I was playing, Kevin Brown had a good one from the right side. I don’t know what would happen if [Alexander] started, but I do know that he’s been really good out of the bullpen. He’s able to give us one inning three days in a row, or he can give us multiple innings. He’s been special for us, and what he has is a unique pitch.”

Alexander on comps and his role: “I hear Zach Britton’s name quite a bit, but when I first came up, Dallas Keuchel was a guy I watched a lot. I felt like we were very similar with our sinkers. I guess that now I’m throwing harder than he does, though.

“Could I be a starter? I don’t know. I have enough to think about being a reliever. I’m just doing what I have to do to get outs — throwing sinkers and trying to get ground balls — and don’t really think about anything else.”

Henry on Alexander’s heavy sinker usage: “Success prompted him to do that. He realized, ‘This is working, so why would I do anything different?’ His other stuff is actually pretty good — he’s got a good slider and a decent changeup — but he doesn’t really need them. He’s doing just fine throwing his power sinker.”

Alexander on his heavy sinker usage: “It was just this year that I went to almost all sinkers. At the beginning of the season, or even more towards spring training, I started getting the idea of doing it. I was talking to Mike Minor about it. I’d given up a couple of hits on offspeed and was kind of frustrated. I told him, ‘Every time I give up a hit it’s on offspeed,’ and he said, ‘Why not just throw your sinker all the time?’ He told me he had a year where he leaned on his two-seam and that my sinker is a lot better than his.

“These are good hitters, so I know I’m going to have to make adjustments, but right now… this is my first full season in the big leagues, and a lot of guys don’t even know who I am or what I throw. They’re going to make adjustments on me, and I’m going to have to make adjustments, as well. How I’m throwing right now isn’t necessarily how I’m always going to throw. But I do know what my strengths are, so that’s what I’m going with.

“If you have one the best defenses in all of baseball behind you, you’d be a fool to not keep doing this. My strength is one of the team’s strengths, and that helps with my confidence. It’s kind of, ‘You know what? If I keep it on the ground, I can feel pretty good about my chances.’ That’s my mindset.”