Red Sox Offseason Target: Kelvin Herrera

The Red Sox are looking for relief help this winter. *Extremely Jay Leno Voice* Have you heard about this? Boston lost both Craig Kimbrel and Joe Kelly out of a bullpen that already ostensibly needed some help to begin with, so they are expected to be looking at most of the top relievers available in free agency this winter. Presumably that includes Kimbrel, who is understandably looking for a ton of money as a Hall of Fame pitcher in his prime. He’s reportedly seeking six deals, though he’s almost certainly not going to get that. He and his agent almost certainly know it, too. It’s unclear at this point whether or not the Red Sox will be willing to spend the money for Kimbrel, but whether it’s him or someone else the 2019 closer is very likely not in the organization as we speak today.

Fortunately for the Red Sox, there are a lot of good relievers on the market this year even if they aren’t quite Craig Kimbrels. We’ll talk a lot about the veteran right-handers out there in the coming days and weeks — unless they go out and sign someone and make it all moot — but we’ll start with the guy I’d deem most likely for them to sign. He’s not necessarily my favorite, but they’ve been connected to him in the media and they were connected to him during the summer as well. Of course I’m talking about former Royals star Kelvin Herrera.

Herrera is a familiar name to most baseball fans for one thing because he’s been one of the game’s better relievers for most of this decade but also because he was part of Kansas City’s famed three-headed monster when they were making their World Series runs. Along with Greg Holland and Wade Davis, Herrera helped kickstart the bullpen revolution we’ve seen around the league and helped make relievers cool again. As someone who writes a national bullpen column every week at BP, I’m appreciative of it. Herrera outlasted both Holland and Davis in Kansas City, but after a long and productive career with the Royals he was dealt to the Nationals this past summer as the first big trade of the 2018 season.

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This is when the Red Sox came in. Washington had a disappointing year and the Red Sox tried to get Herrera from them at the trade deadline. Apparently the Nationals had a change of heart at the last second, held on to Herrera for the rest of the year and the Red Sox opted to add no relievers at all. Obviously this worked just fine for Boston, but it’s telling that it was essentially Herrera or bust for them on the trade market. With that being the case, it only makes sense that he’s going to be a big target for them in free agency as well. There haven’t bee any hard rumors connecting the Red Sox and former Royals star, but Rob Bradford did talk about the connection in a column earlier this week.

So, we know the Red Sox could be interesting in the righty at some point this winter, but what about his actual skills as a pitcher? Well, looking at his 2018 it was something of a tale of two halves. Before the trade to Washington, Herrera was lighting it up on a bad Royals team. In 27 appearances with Kansas City he pitched to an impressive 1.05 ERA with a 2.72 FIP and a 3.88 DRA. Much of his success came from incredible control as he issued just two free passes in 25 ²⁄₃ innings. Things weren’t so good with the Nationals, however, as he pitched to a 4.34 ERA, a 5.64 FIP and a 4.20 DRA over 18 ²⁄₃ innings with a walk rate close to four per nine innings.

Looking a little more closely at his 2018 season, two things stand out to me. For one thing, he only struck out 7.7 batters per nine innings, an extremely low number for a late-inning, right-handed reliever in today’s game. Granted, Herrera has never really been a big strikeout pitcher late in games having only struck out at least a batter per inning twice over his seven-year career. Still, the 7.7 per nine was the second lowest of his career at a time when batters are striking out more than ever. Per Baseball Prospectus’ plate discipline numbers, his swinging strike rate is right in line with his career norms, but a higher percentage of the whiffs are coming on pitches out of the zone. That can still work, but more contact in the zone can be a sign of diminished stuff. There’s nothing major that can be seen on Brooks Baseball. Herrera has seen a slight drop in fastball velocity, but it’s still at 97 mph and less than a tick lower than the previous few years.

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Beyond the strikeouts, Herrera also saw a big increase in fly balls and this is more of a concern to me. As I mentioned, he’s never really been a big strikeout guy but has succeeded because he could limit hard contact in the air. He’s never been an elite ground ball guy, to be fair, but has regularly maintained a rate in the 46-49 percent range with a few years over 50 percent (per Baseball Prospectus). In 2018, that ground ball rate fell to 38 percent and all the way down to 36 percent with the Nationals. As a result, he allowed more homers than usual and that becomes even more concerning heading to the American League East. Fenway in particular may not be a huge home run park, and Boston’s outfield defense is a boon for flyball pitchers in general. However, if you don’t have the stuff for strikeouts you’re asking for trouble with fly balls in parks all around the division, including Fenway for doubles and triples. Over the last two years Herrera has abandoned his sinker, and between the diminishing swinging strikes off his four-seam and the increasing flyball rate, any team that signs him may want to consider bringing it back.

We’ve gotten this far, but we haven’t even talked about the thing that will most diminish his market this year: The injury. Specifically, Herrera suffered a torn Lisfranc ligament in his foot while with the Nationals that prematurely ended his season. Bradford talks about it at length in the post linked above. In it, Bradford mentions that Herrera is progressing nicely. It’s even possible he’ll be ready for the start of the regular season, though a delay of a few weeks is more likely. On the one hand, that injury may help explain some of the rough numbers with the Nationals, but it will also dampen the market for the soon-to-be-29-year-old.

So, should the Red Sox be interested? Like everything else, it depends how much it costs! According to experts around the interwebs, pretty much everyone agrees that he’s only going to get a one-year deal, presumably so he can try to re-establish value and re-enter free agency next year. If that’s truly the case, the Red Sox should be all over it. Herrera is still under 30 and has a track record of great success in this league. I’d feel a lot better if he was a secondary signing along with a Kimbrel, a David Robertson, an Adam Ottavino or someone like that, but in a vacuum at least Herrera makes a ton of sense.