Alcantara is one of those guys who has a huge arm and tantalizing potential when you see him live, but who has also struggled to put it all together since coming over from the Dominican Republic in 2011.  The velocity and life on the fastball is there – he sits 92-to-94 mph and was up to 95 for me at the end of July, while showing some run and tail late to the arm side, and cutting it to the glove side.  He also sports a ¾-depth slider that is inconsistent, but showed average to slightly above average at 82-to85 mph.  He has long legs and a high waist, and he can really whip the arm through the slot and generate some arm speed.  He gets good angle and while he has some effort, it is relatively smooth and repeatable.  Sounds enticing right?  So why does a kid with a plus fastball and chance for an above-average slider have a career 4.69 ERA through 412.1 IP as a professional?  I suppose it depends on who you ask, but the 5.1 BB/9 and the 6.7 K/9 career marks should shed a little light on what the issues are.

Up until 2013, Alcantara was used almost exclusively as a starter – not uncommon for kids with big arms at the lower levels, as clubs want to see what they have due to the ever increasing value of quality starting pitching, plus the developmental value in getting 80-to-90 pitches every five days.  Alcantara struggled in the rotation as he really never was able to limit the walks and pitched to almost a 1:1 SO:BB ratio through 2013.  In 2014 he only made seven starts and 20 appearances out of the bullpen, however he did not fare much better out of the pen–23 hits through 15.1 IP with 10 walks and 11 K’s.  However, in 2015 as a full-time reliever, Alcantara responded to the tune of 4.6 BB/9, 8.6 K/9 and 8.1 Hits/9 through 74.1 IP – improvements from the respective 7.1, 5.0 and 12.5 marks through 43.1 IP the year prior.  That progression has continued in some respects in 2016 as Mario has only given up 45 hits through 67 .2 IP in his first season in High A.  However the K and BB rates has both regressed slightly (5.5 BB/9 and 6.7 K/9).

What that tells me is that the late life in the zone I saw has been consistent, and that this kid is tough to square up.  While the slider is inconsistent, he did throw it for strikes in my look and that that has probably been the norm for him this year, and enough of a wrinkle to keep High A hitters off balance.  The drop in K’s shows that he is having trouble putting guys away, likely due to the inconsistency of his breaking ball, and not being in good counts often enough to get guys to chase.

Ultimately, this all comes down to fastball command, something Mario has struggled with throughout his young career.  He has shown some signs that he may be making some strides, but he will need to do a lot better to continue climbing.  What you see at the field is exciting and makes you want to dream a bit, however when you look at the numbers you see a track record of inconsistency and concerning command issues.  At 23, he is considered a bit of a “mature arm”, so the upside is going to be limited going forward.  However he has the type of power stuff that could propel him upwards pretty quickly if the command clicks.  He is approaching his six-year free agent mark and should be a prime target for other clubs this offseason if Boston doesn’t resign him. My full report on Alcatera can be found here.