With both Bobby Jenks and J.J. Putz leaving the South Side this offseason, the Sox will be missing lot of high leverage work from the right side, 3 WAR according to Fangraphs. Sergio Santos will be expected to shoulder a big chunk of that load after a very effective rookie season that still managed to leave a lot of questions. Those more pessimistic will point to his scant experience. Those more optimistic will point to his top notch stuff. As with Chris Sale, we're ultimately left with guesswork.
Let's start with the tape. I watched a couple of his late-season outings, some dominant, some less-so. The main thing that struck me was the streakiness of his command. Coop and AJ clearly wanted him to nail down the fastball away for strike one this past season and though there were many instances of him hitting the glove spot on, there were times when the command would up and leave, without saying goodbye. The heater would skirt across the plate or dart low with regularity and without intent. That's the primary difference between Sale and Santos and the one most likely to keep the latter in the pen for some time, if not the duration of his career. Sale worked in and out, hitting the glove and missing away from the plate while AJ moved with him. By and large Santos was given a single spot to hit with his fastball: low and away.
To be sure, this is all as you might expect for a guy with only two seasons of professional experience pitching. And with the negatives come positives. For one, he's a former shortstop picked in the first round so he's definitely an athlete. This becomes apparent watching him pitch. It's not exactly a smooth delivery, but it looks repeatable and athletic to my eye. Two, it's not unreasonable to expect better and better numbers as his approach becomes less and less rudimentary. For instance:
As you can see, they're very similar pitches but Bobby gets more whiffs per swing despite throwing his (slower) pitch more often. This becomes more pronounced against RHB, where Bobby gets 9% to Sergio's (probably below average) 6%. I'd guess the reason is largely due to location. Sergio was away, away, away while Bobby definitely knew how to climb the ladder. Sergio really doesn't have much feel for the top of the zone at this point and he's missing out on groundballs and K's. Remember, Santos' fastball is in the neighborhood of the Thornton/Dotel style. Lots of rise, relatively little run. It's not as good, so let's not expect 10%+ like those guys, but his four seamer can get whiffs. It's just that for now his location isn't there. If he can figure it out, opposite field flies and liners will turn into jamshots and whiffs. As it stands, I expect his HR allowed to regress significantly (just 2 in 50+ IP for '10) if he doesn't find an additional spot for his fastball.
But the real point for optimism lies in Santos' offspeed stuff:
The most obvious plus is that whiff rate. Well above average for his two primary offspeed offerings. His slider is just sick in conjunction with his fastball. The tape I watched featured a number of major leaguers doing their damnedest not to swing at anything but his fastball and failing. They were doing exactly as they should against a guy with Sergio's limitations. Sit fastball away and try to drive it, especially if he grabs too much plate (as Mike Lowell did for a double in his last AB at the Cell). But they couldn't consistently do it as long as Sergio got a slider in the neighborhood of low and away. There's just not enough time to figure out which is which.
His change isn't quite as good, but it's still a plus pitch. I think part of the problem with the change is the significant difference between its action and the fastball. The heater is a riser while the change runs a lot. He really pronates on the change and gets, as Orel Hersheiser put it, screwball action with nice dip and run, though it might be a little too hard. There are a decent number of guys in the minors throwing sinkers that look just like Sergio's change. There's room for improvement, but he's got an obvious feel for the pitch. I saw him throw it a surprising amount to same-handed batters, which I'd like to think suggests a certain comfort.
The nice thing about stuff that good is that neither pitch requires a lot of command to really get good use out of them. Aim low and away from the batter and the results will be there. This likely explains Coop's focus on hitting the outer half with the fastball. Keep it out there and you'll set up a lot of K's which of course is what Sergio got, to the tune of 10 per 9 IP. Just like the fastball, he exhibited a very basic approach. He seemed to consistently try to bury both pitches when he missed and got very few strikes looking on anything slower than 95 mph.
Going forward, the key to his development will be to get his spots down and then to start playing off batters expecting a simple approach. Once you see him hitting AJ's glove with consistency, look for the glove to start moving under the hands of batters. On top of that, look for comfort with throwing offspeed both earlier in the sequence and when behind in the count. He's going to have to be willing to hit more of the plate which could mean struggles in the short term. If he can't, he's going to have a hard time filling Bobby's shoes. MLB batters, even against his stuff, are just too good when they can guess what's coming. At this point, I think we'll see more or less a repeat from 2010, but with regression on his HR rate. Just for kicks, I'll guess he puts up a 3.90 ERA. It's hard to get a lot of work as a reliever, so it'll be tough for him to really get the reps he likely needs to develop rapidly.
That said, I'd really really like to see him groomed as a starter. There's just so much to like. In my most optimistic moods, I see him first replacing Thornton after this season and then Peavy when Rick Hahn buys him out after 2012. He's got three plus pitches and a sturdy build which at least suggests he could handle the workload. The Sox are going to need to reload on starters soon enough and the only thing standing in Sergio's way is that he's missing a load of reps that everyone else got years ago. If he can turn himself into a starter on this staff, it'll be a huge testament to both his athleticism and his work ethic. He's got a long way to go.