Just how good will the Red Sox rotation be?

Not long ago, on December 6th, the Boston Red Sox completed a blockbuster trade with the Chicago White Sox to add Chris Sale to their rotation. Boston gave away a significant haul of talent to get Chicago’s ace, but the rationale is simple: win now.

Simply put, Sale makes an already-impressive rotation even better. With his presence — and despite some minor causes for concern — Boston profiles to have an elite rotation in 2017.

Last season, the Boston Red Sox were one of the top teams in baseball on the strength of a fire-breathing offense coupled with a solid pitching staff. They flamed out against Cleveland in the first round of the playoffs, but are returning most of their core for another run in 2017. Adding players like Sale (despite the high cost) presents the best way for this team to get even better.

Here, then, is one of the most important parts of this equation: Boston already had a good rotation before adding Sale. According to FanGraphs, the Red Sox ranked in the top 10 in the league in several metrics. In Wins Above Replacement, for example, the team’s starting pitchers ranked seventh (right in between Cleveland and San Francisco) with 13.9.

Boston also ranked seventh in WHIP (1.27), and eleventh in FIP (4.16), suggesting again that the team’s rotation was already in the upper third of the league by most metrics. And if you want to get really advanced, the Sox placed sixth in DRA at 3.99 and 11th in cFIP at 98.

The Red Sox got to this level largely on the strength of their three best starters — David Price, Rick Porcello, and Steven Wright — who combined for 12.5 of the rotation’s 13.9 WAR for the season. The other three starters who pitched at least 60 innings recorded only 1.9 in that category.

Meanwhile, pitching for a struggling White Sox team, Sale recorded impressive numbers of his own. His WHIP/FIP/WAR stats equaled 1.04, 3.46, and 5.2, respectively (according to FanGraphs). All these statistics rank well above Boston’s already-impressive 2016 numbers, and one can only imagine that Red Sox fans must be salivating at the thought of replacing the inconsistent Clay Buchholz with a pitcher of Sale’s caliber.

Another factor to consider is Sale’s (and Boston’s) durability in an age where it is increasingly valuable. In 2014, there were 34 pitchers who threw 200 innings. In 2015, that number fell to 28. In 2016, only 15 pitchers recorded 200 innings. Regardless of how arbitrary a number 200 may be, it’s hard to argue with the conclusion: pitchers who can throw high numbers of innings for entire seasons are in short supply.

Two of the fifteen pitchers in baseball who threw 200 innings — Price and Porcello — were already on the Red Sox. By adding Sale, Boston now has one-fifth of the 200-inning starters from last year. This, ultimately, may be one of the most important statistics. High-level talent is considerably less remarkable if it comes with health concerns (this is a dilemma that several teams faced when considering Rich Hill this offseason). Now, though, the Red Sox can put three consistently elite starters on the field with a reasonable amount of confidence that each player can handle his full-season workload.

Of course, there are some (slight) reasons for concern. Price famously got off to a poor start last season, and — even though he rebounded to have a fine year — his season-by-season numbers in K/9 and BB/9 are all trending in the wrong direction. This isn’t terribly surprising or concerning since he is 31 years old, but his best years may be behind him at this point. Sale’s FIP numbers have also taken a slight hit, rising from 2.57, to 2.73, to 3.46 over the 2014, 2015, and 2016 seasons, respectively. Sale is younger than Price, at 27, but it’s reasonable to expect that he might begin to tail off a little, as well.

However, none of these facts suggest that the Boston Red Sox are going to have anything short of a fantastic pitching staff this season. If one considers their 2016 rotation as a solid top-10 unit, it’s conceivable that Sale’s presence could catapult them into top-five, or even top-three, status if all goes right. Boston gave up a lot to get Chicago’s ace, but it is impossible to argue that the Red Sox aren’t better equipped for 2017 now. Already primed for contention this summer, Boston is taking another step forward.

Thomas Jenkins is a writer for Beyond the Box Score and Peachtree Hoops. You can also follow him on Twitter for tweets about sports.