When David Robertson first broke into the Majors with the Yankees in 2008, he was not all that dissimilar from what Shawn Kelley is today. He had stuff for days and had a long list of strikeout victims to back it up, but he was so hot and cold with his command that he could get into trouble quickly. D-Rob's "fireman" knack for getting out of jams and making his best pitches in big moments earned him a permanent spot in the 'pen almost from the moment he came up, and over the last 5+ seasons he's worked his way up the ladder to become Mariano Rivera's setup man and one of the best all-around relief pitchers in baseball. While many other pitchers have tried to learn from the G.O.A.T., perhaps none have taken more away from working with Mo than D-Rob.
This season, Robertson has pitched to a 2.76/3.09/2.82 slash in 16.1 innings. He's gotten burned a bit on some homers, but his strikeout rate is as healthy as ever, his velocity is up, and he's got a solid GB rate. Most importantly, D-Rob is putting up his 4th straight season of decreased walk rates, down to 2.20 BB/9 and just 6.4 BB %. Robertson has tightened up his mechanics over the years, become much better at repeating his delivery and release point, and has learned to harness his great stuff and maximize its effectiveness by locating better and throwing more strikes on the corners. Sound like anybody you know?
In fairness and respect to D-Rob, I'll say that there likely would have been improvement in those departments naturally as Robertson worked with better coaches, other players, and on his own to hone his craft. Where the lessons of Mo really start to become obvious are in Robertson's pitch type trends. After spending his first couple years as an almost exclusive 4-seamer/curveball guy, Robertson started throwing a cutter in 2011. By just the next season the cutter had become D-Rob's primary pitch, 53.5% of all pitches he threw last year according to PITCHf/x, compared to just 27.4% 4-seamers. And it's not just something he throws in homage to Mo, it's a plus pitch. So far this season his cutter usage has dropped a tick to 50.9%, and that's primarily due to Robertson bringing his curveball back more after using it less than 20% for the first time in his career last season. When your curveball is as good as D-Rob's (31.3% whiff rate), that's a great tradeoff.
So smooth, repeatable mechanics, plus pitch location on the corners, cutter-heavy pitch selection. That's the Mariano Rivera playbook right there. Obviously D-Rob isn't an identical version of Mo because he throws a few more pitches, but he's applied Mo's techniques to all those pitches and how he goes about pitching and he's become a better pitcher for it. When Robertson is really locating his fastball, like he was in his appearance earlier this week, he's almost unhittable because of how good his curveball is. And when he's not, he's learned how to work around it and still be effective. He can come out and blow you away or he can pitch smart and get you to make the weak contact he wants. Not too many other non-Mo pitchers out there who can say that.
David Robertson is a 28-year-old valedictorian of the Mariano Rivera School for Relief Pitching. Someday, they're going to name the library on campus after him. He's proven himself to be the right man for Mo to pass the torch to when he retires after this season and the Yankees' decision to let Rafael Soriano walk is an indication that they've finally figured that out. There hasn't been much talk about D-Rob's future in pinstripes yet - he has one more year of arbitration eligibility left - but it's something the Yankees should and probably soon will consider. It would be both a smart business and baseball move to lock him up long term before he hits the open market.