The Boston bullpen was good, but it just got better.

When the Boston Red Sox signed David Price, there was another shoe that had to drop some time—with their rotation bolstered by Price, they were going to trade one of their existing starting pitchers. Well, now we know what that trade is:

Miley and aro to mariners for carson smith and roenis Elias agreed to

— Jon Heyman (@JonHeymanCBS) December 7, 2015

Elias will move into a backup starter role, but Carson Smith may be the most impactful piece in this trade.

For a bit of historical context, first let's look at the pitch movement chart from another player: currently-rehabbing-Ray Jonny Venters, back when he was the counterpoint to Craig Kimbrel in the once-amazing Atlanta Braves bullpen.

That's 2012, and Venter's impressive sinker spun in at 93 mph. It was one of the baddest groundball inducers in the land.

Now here's Smith from last season:

Smith's is about a mph slower than Venters' was, on average, and it comes from the right side rather than the left, but the speed on the slider is the same and the comparison is clear. Carson Smith has a sinker-slider repertoire that should make Jonny Venters jealous, and that makes him an annoying new beast to suddenly have to face in the bullpen of an American League East rival.

For those of you who like to see results rather than just dots on a graph, here are Smith's stats from last season: 70 innings pitched, 32.4% strikeout rate, 7.8% walk rate, 64.8% groundball rate, 2.58 ERA, 2.12 FIP.

He joins a bullpen that besides Kimbrel already has talent in Koji Uehara and Junichi Tazawa. Rats.