The Brad Boxberger signing by the numbers

Yesterday the Cubs signed veteran reliever Brad Boxberger to a one year, $2.8 million contract. It’s a move that many Cubs fans will be familiar with. The team has added a relatively affordable, proven bullpen arm. The contract is attractive enough that when if the Cubs are out of contention in July, other teams will certainly be willing to part with a prospect to add Boxberger to their bullpen at the trade deadline. Let’s take a look at the numbers behind the signing.

The pitches

Boxberger relies on three pitches, according to Statcast. He throws a four-seam fastball 55 percent of the time. He pairs that fastball with a change-up he throws 22.6 percent of the time and a slider he throws 22.5 percent of the time. Justin Choi at FanGraphs wrote up Boxberger last March when the righthander re-signed with the Brewers and noted:

That’s right. Boxberger, the point in yellow, generated an above-average strikeout rate for a reliever (31.2%) while having the fourth-lowest chase rate (20.6%). Not that more chases automatically equals more strikeouts, but this is still pleasantly odd. Boxberger doesn’t need to fish outside the zone to rack up strikeouts – he meets hitters in the middle, and more often than not, he emerges victorious.

Making things confusing is that he doesn’t have remotely the best stuff. His primary weapon is a four-seamer featuring run-of-the-mill velocity and movement. It’s not like he throws from a funky arm slot, and his vertical approach angle isn’t conducive to pitching at the letters, either. His secondaries, a slider and a changeup, are fairly bland as well. But Boxberger does have one unique trick up his sleeve, and that’s the pace of his delivery.

What’s pretty wild about Boxberger is that despite “run-of-the-mill” pitches, he gets exceptional results, which must be what the Cubs are hoping they can harness at Wrigley Field.

The results

Anytime I see a Statcast profile with this much red, I am intrigued:

Statcast

Boxberger might not get a ton of chase on his pitches and he might walk a few too many guys, but whatever he’s doing results in extremely weak contact and well over league average strikeouts.

Speaking of strikeouts, that K rate has fluctuated pretty wildly over the years, which leads me to be cautious about dreaming on an 11+ K/9 with the Cubs, but it seems like the Steamer projection for Boxberger to regress to below a strikeout per inning may be a bit pessimistic. You can see Boxberger’s K/9, along with other key stats and his 2023 projections according to Steamer below:

It also seems worth noting here that Boxberger has experience closing. He has two seasons (2015 and 2018) where he had more than 30 saves. Given the uncertainty and lack of experience getting the final three outs in the back of the Cubs current bullpen, Boxberger gives the Cubs a nice option to potentially close out games.

Take aways

We’ve seen this movie before — Jed Hoyer signs a veteran reliever (or three) to a one-year deal which provides a pretty serviceable back end of the bullpen along with the flexibility to flip all of those guys for prospects if the team isn’t competitive in July. Boxberger provides a solid option for David Ross to deploy in the late innings, but unless the Cubs add some impact bats, I imagine he’ll finish the season with another team.