Just when the Yankees thought they had rid themselves of a Northwestern University presence with the firing of Joe Girardi over the offseason, in comes J.A. Happ in a trade with the Blue Jays. The first Northwestern pitcher to ever pitch in an All-Star game (h/t to my friend Mark McCann), and also the first Northwestern pitcher to allow a home run in an All-Star game, Happ has enjoyed a career renaissance over the last two-plus seasons, seemingly turning his career around after a deadline deal to the Pirates in 2015. Prior to that, Happ had consistently had an ERA in the mid-to-upper 4.00's, but since then has shaved about a full run off his ERA (though it's a touch higher this year).

All that's well and good, but why did the Yankees trade for him? First, he adds depth to a rotation that is missing Jordan Montgomery and Jonathan Loaisiga to injury, and has tried out Domingo German and Luis Cessa to fill the bottom of the rotation. The Yankees enter Sunday's play 5.5 games out of the AL East lead behind the Red Sox - they can't afford to give up an edge in any single game if they hope to catch them, which they obviously do. Teams can make runs from the wild card spots in the playoffs, but anytime you can avoid a one-game play-in, and give up home field advantage, you do so. This is especially pertinent to the Yankees, who are 21 games over .500 at home, but just eight games over .500 on the road.

Moreover, it's those same Red Sox they're likely to face if they get through the play-in game. And that's where Happ is more important. The Red Sox pound right-handed pitchers, slugging .474 against them, while posting a league-leading .348 wOBA and 117 wRC+. Their numbers against left-handers are more average - .416 SLG, .321 wOBA and 99 wRC+. Meanwhile, the Astros and the Indians are among the best in baseball at hitting lefties. So it's pretty clear that this was made with the Red Sox in mind. In two starts against the Red Sox this year, Happ has allowed six runs (one earned) over 10.2 innings, with a 16:1 K:BB and one homer allowed. But that's a little deceptive - his first start against them in April was a gem - seven innings, one run, 10 strikeouts. His second start, two weeks ago on July 12, didn't go well - he lasted 3.2 innings, allowing five unearned runs, the last four on a grand slam by Mookie Betts. He did at least strike out six. He also faced the Red Sox (albeit without J.D. Martinez) four times last year, allowing only seven runs (five earned) in 23.2 innings. So the overall body of work against them is pretty strong.

This move has the appearance of matching the Red Sox's move to acquire Nathan Eovaldi, who has pitched well in two outings against the Yankees this year. Likewise, the Yankees are to left-handers what the Red Sox are against right-handers. That dynamic might have been changed, however, by Aaron Judge's wrist injury Friday night. Both Eovaldi and Happ make their respective debuts for their team on Sunday, and then are slated to face each other next Saturday.