During the massive disappointment of the 2014 season, the Red Sox have been busy acquiring hitters: Yoenis Cespedes from the A's, Allen Craig from the Cardinals, and Rusney Castillo from Cuba being the most notable additions to the team's line-up. The team has not been shy about the fact that this strategy has a second act, as it will aggressively pursue pitching upgrades this winter since the market will be more flush with arms than bats. And given that the Red Sox already declined to pay market price for one of the winter's best free-agent starters, it seems likely that the team might be more interested in trading for pitchers rather than attempting to outbid others for pricey free agents.
Which brings us to Mookie Betts. If we believe the Red Sox are likely to pursue big trades for premium starting pitching this winter, Betts is likely going to be the piece that everyone asks for. His dynamic debut has increased his value by establishing that his skills can translate to this level, but the Red Sox roster makes his future in Boston still a bit uncertain. He's a natural second baseman blocked by Dustin Pedroia; Betts converted to play center field, only to see the team spend $72 million on Castillo, rumored to be a plus defender in center himself. Betts could play right field, but one assumes that the Red Sox would prefer to let Shane Victorino win his job back next spring. And Betts has played far too well to head back to Triple-A.
So, a trade does make some sense, especially if putting Betts on the table opens the door to acquiring a young, lower-cost ace -- think someone like Chris Sale or Stephen Strasburg -- which would still allow the team to use its cash reserves to make a run at one of the big free-agent starters, rebuilding its rotation in a big way. But as tempting as that idea might be, I have a suggestion for Red Sox GM Ben Cherington: keep Mookie Betts. You might really regret trading him, even for an ace.
Due primarily to his size (5-9) and the potential limits that puts on his power, Betts has not generally been viewed as a franchise cornerstone type of prospect the way Xander Bogaerts was as he ascended the ranks. And while it might seem unfair to make generalities about Betts' future based on his height, there is merit to the idea that he probably won't become a big-time power hitter in the big leagues. For example, we can look at Betts' approach at the plate, and see how players with have a similar attack have fared as big leaguers.
Against big league pitching, Betts has swung at 36 percent of the pitches he's been thrown, and he's made contact on 88 percent of his swings. This is both a very low swing rate and very high contact rate for a big league hitter, with league averages at about 46 percent and 80 percent, respectively. Betts is a guy who not only doesn't chase pitches out of the zone, but is selective in the kinds of strikes he will chase. And he rarely swings through pitches when he does decide to swing.
In the seven years that we have PITCHF/x data, here are the hitters who have posted similar swing and contact rates, along with their isolated slugging (SLG-BA, a measure of a player's power) numbers:
Swing/contact rates
| Player | Swing% | Contact% | ISO |
| Brett Gardner | 35% | 89% | 0.126 |
| Matt Carpenter | 36% | 88% | 0.141 |
| Joe Mauer | 37% | 88% | 0.138 |
| Daric Barton | 38% | 86% | 0.111 |
| Chone Figgins | 38% | 88% | 0.064 |
| Craig Counsell | 38% | 90% | 0.089 |
| Tony Gwynn Jr. | 39% | 87% | 0.074 |
| Elvis Andrus | 39% | 87% | 0.073 |
| Sam Fuld | 39% | 89% | 0.099 |
This is the approach profile of players who don't hit for power. Guys who can do a lot of damage on contact swing at a higher rate of strikes -- among qualified hitters, only Carpenter and J.J. Hardy have swung at a lower rate of pitches in the strike zone this year than Betts -- as to not pass up chances to try to hit the ball over the fence. Guys who swing as rarely as Betts does aren't too passive; they just know their own physical limitations and have adopted an approach that maximizes their ability to get on base.
Mauer aside, this isn't the sexiest list of players around, and perhaps showing that Betts shares some traits with Craig Counsell and the Tony Gwynn who won't end up in the Hall of Fame isn't the best way for me to make a case that the Red Sox shouldn't swap him for an ace this winter. But let's not forget how valuable Carpenter has been to the Cardinals the past few years as an underpowered corner guy who gets on base enough that the lack of power isn't really a problem. Or, perhaps even more accurately, let's look at a guy who didn't quite the list above, but whose skillset shares a lot in common with Betts: Ben Zobrist.
Zobrist's name doesn't show up above because his career contact rate is "just" 84 percent, and I set the filters to show players between 86 and 90 percent, since Betts is at 88 percent this season. That was a pretty arbitrary decision on my part, though, and if you look at Zobrist's swing profile next to Betts', you can see the similarities across the board. First, here are the swing metrics for both:
Swing percentages
| Player | O-Swing% | Z-Swing% | Swing% |
| Mookie Betts | 19% | 51% | 36% |
| Ben Zobrist | 23% | 56% | 39% |
Betts has swung a little less this season than Zobrist has over his career, both on pitches outside the zone (the O in O-Swing) and on pitches inside the zone (Z-Swing means Zone-Swing), but Zobrist isn't some unrepentant hacker. He looks aggressive compared to the extremely patient Betts, but he's far more disciplined than the average big leaguer. Now, for his contact profile:
Contact percentages
| Player | O-Contact% | Z-Contact% | Contact% |
| Mookie Betts | 73% | 92% | 88% |
| Ben Zobrist | 71% | 90% | 84% |
This is where the comparison really works, as their swing results are very similar, both on pitches in and out of the zone. Unlike the other players listed above, though, Zobrist does have a bit of real power, running a .165 ISO over his career; for reference, Betts is at .152 through his first few months as a big leaguer. He's not a slugger or anything, but combining even average power with this kind of command of the strike zone creates a pretty good big league hitter.
And while we're obviously dealing with too-small samples in Betts' case, here are some numbers since Zobrist's 2008 breakout compared with Betts' big league performance to date.
Betts: .285/.362/.436, .356 wOBA, 125 wRC+
Zobrist: .268/.363/.441, .352 wOBA, 125 wRC+
Betts has done this for fewer than 200 plate appearances, while Zobrist is over 4,000, but we can say that Zobrist is proof on concept for the skillset. While it doesn't guarantee that pitchers won't make adjustments and exploit some unknown hole in Betts' swing, we can be fairly confident that he's performing at a sustainable level of offense given his skillset.
And of course, Zobrist has more in common with Betts than just his approach at the plate. He also got to the big leagues as a middle infielder who profiled better as a second baseman, but has also spent a significant part of his career in the outfield and has never really settled in at one single position. This positional versatility has been particularly useful to the Rays, who have used Zobrist in different spots depending on their need at that particular time.
Perhaps there isn't one obvious spot for Betts in Boston, but that doesn't mean there won't be a spot for him in each year, even if it's not the same spot every year, or even every day. As Zobrist has shown, you can be immensely valuable without ever having a single defined role.
Keep in mind that since the start of the 2008 season, Zobrist has put up +37 WAR, an average of more than +5 WAR per season for over the past seven years. Here is the full list of pitchers who have posted a higher WAR than that over the same time frame: Justin Verlander, Cliff Lee, and Felix Hernandez. And only two position players -- Miguel Cabrera and Evan Longoria -- have bested Zobrist's mark on the hitting side.
Maybe Betts won't ever be quite as good defensively as Zobrist, but even if you think he might end up as Zobrist-lite, that's a pretty easy +4 WAR player. Right now, at age 21, the Steamer projection system projects Betts as a +3.3 WAR player, and that's with an assumption of average defensive value in center field. If you include the potential for above-average defense at second base, the forecasts think Betts is already in that +4 WAR range right now, and he's nowhere near normal prime age for a hitter.
Given a few more years of development, Zobrist's level of performance is an entirely realistic outcome for Betts. And while the idea of having a #1 starter in 2014 might be appealing, you don't want to give up six years of club control of a player with that kind of potential, especially when he's already a valuable big leaguer. No one should ever be completely untouchable in a trade, but Betts has demonstrated significant value not only in the future but also in the present, and the Red Sox should be very cautious before shipping him out for a pitcher.
Pitchers are nice until they break, something they're doing at ever higher rates recently. Rather than giving up Betts' future for what might very well be a minimal upgrade anyway, the Sox may very well be better off keeping their young second baseman/outfielder and letting him grow into the new version of the game's ultimate utility player.
