When I try to identify potential breakout prospects in the early-goings of the minor league season, I tend to focus on the single-A levels looking for pitchers who are performing well while being young for their respective level. Enter Felipe Rivero. The Tampa Bay left-hander is currently off to an excellent start with the Lo-A Bowling Green Hot Rods in the Midwest League, sporting a k/9 of 9, a bb/9 of 2.41 and an hr/9 of 0(!). That’s not a misprint! Rivero has yet to allow a homer in 2012.
Rivero wasn’t exactly unheralded coming into 2012, as he ranked ninth on Baseball America’s Appalachian League top 20, but he finished only 28th in their organizational rankings, which is a tribute to the organization’s depth more than anything. The knocks coming into the season on Rivero were his size (6’0’’ and 151 pounds) and the lack of development in his secondary pitches to go along with a mid-90’s fastball. His statistical profile also suggested that he struggled keeping the ball down in the zone, yielding over one home run every 9 innings in 2011.
The biggest thing for me, though, was that Rivero pitched all of 2011 in short-season ball, where you generally have to take performance with a grain of salt. The age of competition can tend to vary wildly at that level, so it was hard to say if Rivero is having success because of an advanced offering or because of legitimate progress. Additionally, Rivero averaged just a little over four innings per outing, providing a poor read for how well his stuff would carry over into longer outings, which is important given his stature. The easy decision when looking at someone his size is to assume that they will become a reliever.
Fast forward to 2012 and Rivero is both proving that 2011 was no fluke and making legitimate progress off of his 2011 campaign. As I mentioned above, Rivero has gone 46 innings in 2012 without allowing a homer. For reference, his pace from 2011 would have yielded five home runs by this time. He has also improved his strikeout rate per plate-appearance by 3%. His groundball percentage has seen a spike of 9% from 2011 as well. In short, Rivero is making progress statistically at keeping the ball down in the zone, which will be critical as he faces more advanced hitters.
The improvement in his strikeout rate has come with a rise in walk rate (up 1.7% from 2011) but that’s not always a bad thing, particularly considering the rate is still under 7% overall. There’s certainly such a thing as being too hittable, and it remains one of my biggest concerns when I see pitchers with low walk rates struggle. Rivero has been luck-neutral in both 2011 and 2012, showing averages on balls-in-play in between 32% and 33% for both time periods. Not surprisingly, Rivero’s improvements in missing bats and avoiding the long ball have yielded a near three-run drop in ERA (from 4.62 to 1.76) and a similar drop in Fielding Independent Pitching (from 4.34 to 1.99).
The Rays are notoriously slow in promoting their prospects, particularly pitchers, so I wouldn’t be expecting Rivero to jump a level anytime soon. He’ll turn 21 in early July, so it’s possible the Rays could give him a taste of Hi-A before the season concludes, but I would still expect the majority of his workload to be at Lo-A in 2012. He has typically had his outings capped at five innings, so one of the biggest markers for Rivero as the season progresses will be how he holds his stuff later in games when he gets the opportunity. I’ll also be keeping an eye on whether the early returns on improved home-run rate, ground-ball rate and strikeout rate hold up for the season. If they do, I think we have a clear top 100 caliber prospect on our hands.