Welcome to our 2020 Red Sox in Review series. This is, as you can probably guess, where we will be reviewing all of the players who made at least a modest impact on the Red Sox in 2020. Every week day we’ll be deep diving into one player. For each edition we’ll describe the season in a sentence, look at the positives from the year as well as negatives, look back at our one big question from the season preview and look ahead to the 2021 season. We’ll be going in alphabetical order of the players on this list. You can look over that list and drop a name in the comments if you think I left anyone out who should be mentioned here. Got it? Good. Today we take a look at the 2020 season for Robert Stock.
2020 in one sentence
Robert Stock didn’t get a ton of chances to make his mark on this season, and even when he did he failed to make a real impression due largely to an inability to throw strikes.
Stock was, to me at least, one of the most intriguing scrap heap type additions made by Chaim Bloom and company prior to and during the 2020 season. The former Padre was originally claimed off waivers from the Phillies in July just a couple days after the season had begun. There was some track record of success at the majors, and along with a big fastball that was enough to get at least mildly excited about the potential. As it turned out, Stock didn’t really get a consistent chance, and to be fair didn’t earn one with the way he pitched.
As far as positives go, though, he did impress with his slider. While the fastball velocity can be the thing that jumps off the page when he takes the mound, it was the breaking ball that performed the best in 2020. Per Baseball Savant, he allowed a wOBA (same scale as OBP) of just .181 on the pitch, and the expected wOBA (based on quality of contact) was only a few points higher. The big righty also was able to miss plenty of bats with the pitch, inducing a whiff on 30 percent of swings.
There are certainly sample size issues abound here — Stock only tossed 13 1⁄3 innings on the entire season — but the slider has been his most effective pitch in all three of his major-league seasons. It’s not hard to see why when you consider both the above-average movement he gets on the pitch in both planes as well as how well he did at getting the pitch to break just below the zone on the glove side portion of the plate.
Getting whiffs on the pitch was great, but the slider was also one of the reasons Stock did a good job of keeping the ball on the ground, another skillset that has been present throughout his career. Again using data from Baseball Savant, the 30-year-old (he’ll turn 31 on Saturday; happy early birthday Robert) boasted a 53 percent ground ball rate. That comes in as the highest of his career, but not by a wide margin as he’s had a rate of at least 50 percent in each of his three seasons in the majors. Given Stock’s struggles with keeping the ball in the strike zone, which we’ll get to more in a second, being able to keep the ball on the ground and avoid extra base hits can go a long way towards limiting big innings. In fact, Stock didn’t allow a homer all year and has allowed just three homers over his 63 2⁄3 career innings.
While there were some flashes that still lead me to believe Stock can be effective depth as a middle reliever at the highest level, at the end of the day he still finished his sporadic appearances in 2020 with a 4.73 ERA, which comes in slightly below average. And when we talk about Stock’s struggles, we have to start with those control issues to which Sara was referring with her tweet above. Stock walked a whopping 16 percent of his opponents in 2020, and while again sample size issues could be involved he also has a career rate of 11 percent. So, control is clearly an issue here just in general. It’s not hard to see why, either, as he both misses the zone frequently (45 percent zone rate) and fails to get enough swings on those pitches (18 percent chase rate).
It is a bit surprising he didn’t get more chases specifically on the slider, but whatever the reason he can’t afford to put all of these runners on for free, particularly since he doesn’t miss as many bats as you would expect from a guy with such a good slider and a fastball that gets up into the high 90s. Despite the stuff, though, he struck out just 22 percent of his opponents, which comes out to an essentially league-average rate. Throw in a hard-hit rate approaching 50 percent, and you are asking for a ton of trouble when combined with all of those free base runners, even if you are keeping the ball on the ground. Sure enough, Stock struggled to put together quick innings, averaging nearly five batters for every three outs he recorded and getting through just one clean outing all year.
The Big Question
Looking ahead to 2021
Stock, as was the case with Springs yesterday (linked above), is currently on the 40-man roster but has no guarantees to make it through the offseason. The Red Sox have Rule 5 decisions to make later this week, and assuming they protect the six prospects who would appear to be slam dunk protections, they need to open up three more roster spots, not to mention any more for free agents that will eventually be signed. That Stock has an option remaining helps his case, but he’s right on the line to where he could find himself back on waivers at some point soon. If he does make it through the offseason, he’d enter next season as a depth option, almost certainly starting the year in Triple-A.