Mariano Rivera Jr. RHP Evaluated 3x in 2017, Most Recently 6/6/17
Fastball (45/50) Slider (40/45) Changeup (30/35) Command (40/40)
Washington’s 4th round pick in 2015, signed for $410,700; 23.5 y/o who is listed at 5-11 155lbs and looks smaller, appears to be wearing his older brother’s uniform; very little to no projection left. Rivera’s a pure relief prospect, pitching exclusively from the stretch and utilizes an almost straight over the top arm slot. He has a fast arm and a short arm swing. His mechanics are not particularly smooth, as his medium leg lift leads into throwing off a stiff from leg and a significant head “whack” after foot strike. Furthermore, he struggles repeating his delivery, hindering both his command and control.
3-pitch repertoire: Fastball (90-93mph, T94) shows late life and occasional arm-side action when he stayed on top; pitch flattens with little plane when he drops his arm slot. The fastball “plays down” due to the lack of movement and command issues. The slider (84-87mph) is extremely inconsistent – at the lower bands he struggles with his location and the pitch becomes slurvy. At the higher velocities it works more like a cutter, sometimes moving away from the barrel and other times finding the heart of the zone. Rivera will throw the occasional (81-83mph) changeup, but it is a subpar offering as he visibly slows his arm down, causing it to resemble a batting practice fastball. I applaud the effort in trying to throw a changeup, but it needs significant improvement to be a major league offering.
Rivera has looked underwhelming in each of the outings I have seen this season. It is concerning he is acting as a non-closer in High-A two years post-draft and struggling against younger competition. He has good fastball velocity and shows the ability to spin a breaking pitch, but his lack of an above-average pitch and mediocre command limits his ceiling. Considering he is a 4th round pick and the son of the greatest reliever in history, he will get more opportunities than similarly talented prospects. However, Rivera profiles as a reliever who stagnates in the upper minors, with the best case scenario being he gets a “cup of coffee” in the major leagues.