Top stats to know: Yankees at Cardinals

The St. Louis Cardinals host the New York Yankees in Game 1 of a three-game series today (4 ET, ESPN). Here are some of the key storylines we will be following.

Average Yankees

The Yankees are three games above .500 despite a negative-six run differential. The Toronto Blue Jays are the only team in the AL East with a positive run differential. Its combined negative-34 run differential is the

worst among the six divisions in baseball.

Yankees This Season

The Yankees are barely playing above league average in several categories this season. They rank 14th in OBP, 12th in slugging percentage, 11th in runs per game and 13th in ERA.

Ellsbury's cooled off

Jacoby Ellsbury was one of the team leaders in batting average and OPS in March and April but has cooled off significantly this month. After batting .312 through April, he's hitting just .200 in May. His strikeout percentage has worsened going from 15.5 percent to 22.2

percent this month.

Jacoby Ellsbury This Season

He has struggled against offspeed pitches all season long, and pitchers have adjusted. Overall, he's hitting .211 with a .507 OPS in plate appearances ending with non-fastballs. In April, he only saw changeups/curveballs/sliders on 31 percent of pitchers; in May that's up to 38 percent.

Wacha is back

Michael Wacha is making his first start since being forced to leave his last game on May 21 against the Diamondbacks after getting hit on his right elbow by a foul ball in the dugout. He did not miss a start.

He hasn't missed a step since bursting on to the scene last year and has actually gotten better. He has increased his strikeouts and

reduced his walks and ERA.

Michael Wacha Last 2 Seasons

Over the last two years, his opponents have produced a .414 OPS in plate appearances ending with his changeup. Only Stephen Strasburg (.369) and Félix Hernández (.414) have had more dominant changeups by that metric over that span.