Kenley Jansen is following in Rivera's footsteps, specifically with the cutter. He's throwing it 94.6 percent of the time this season, according to Brooks Baseball.
When a relief pitcher has such a dominant pitch as Rivera and Jansen, it's not surprising to see them throw that pitch almost exclusively. But those pitchers are rare.
Paco Rodriguez has a nice three-pitch mix, but he's throwing his 4-seam fastball just 20.8 percent of the time this season. In his brief 2012 debut, he threw his fastball 41.6 percent of the time. The scouting report on Rodriguez out of college was his fastball sat in the low-90s. In his brief career, he's averaging exactly 90 MPH on the pitch -- the lowest of the 90s. He's resorted to his cutter and slider much more than his fastball this season, which isn't necessarily a bad thing. Rodriguez is throwing his cutter 39 percent of the time and his slider 32.5 percent of the time.
Rodriguez throws his fastball less than every pitcher in baseball not named Rivera, Bryan Shaw and R.A. Dickey.
Both pitches are effective against both kinds of hitters, but his fastball is a weapon that's underutilized so far.
*Pitch values, according to FanGraphs
His fastball is less valuable while his cutter is more valuable this season, so that accounts for the lack of fastballs so far. But if Rodriguez wants to have continued, sustained success in the majors, he'll have to learn to trust his fastball more.
His slider and cutter have similar vertical movements, illustrated in the chart below.
Rodriguez will need to be able to change the hitter's eye so he's not always expecting a pitch with some sort of bend. That's a good thing because at this rate, it's a surprise when he throws a straight fastball. It stands to reason hitters could be surprised by the fastball. Since Rodriguez is going to pitch in a lot of high-leverage situations, he'll need all his weapons working while on the mound.
It's nice to see him have such confidence in his off-speed offerings -- especially at a young age. But in most cases, a pitcher is only as good as his fastball. Rodriguez could be a damn good late-inning reliever -- especially if he harnesses and embraces his fastball.
It's rare for a hard-throwing reliever to have a legitimate three-pitch arsenal, but Rodriguez is one of those guys. He's going to be good for a really long time.
Photo credit: Dustin Nosler, Feelin' Kinda Blue