I can't imagine there was a scenario where Joe envisioned things being so bad in his rotation this year that he had to use Chase Whitley as a regular member of it. Even the worst of your average worst-case scenarios don't get that bad. When CC Sabathia joined Michael Pineda and Ivan Nova on the DL in mid-May, that worst-case scenario came about in real life and the Yankees were forced to go to the Whitley well. The move proved to be a good one for a while. Whitley allowed 2 ER or less in 6 of his first 7 starts, 3 in the other, and gave the battered rotation a needed boost by eliminating walks and keeping the ball in the ballpark.
Right around the time that he got stretched out to a comfortable starter's pitch count, however, the performance started to sour and sour in a hurry. Whitley gave up 8 ER in only 3.1 innings against the Blue Jays on June 23rd, his first time facing a team for a second time, and followed that up by allowing 5 in 4+ innings against the Red Sox on June 29th. 1 more bad start against the Twins in early July in which he didn't get out of the 4th inning and Whitley was booted from the rotation only to return on Sunday as an injury replacement again, this time for Masahiro Tanaka. A scoreless 3 innings to start that game quickly turned to a 3-run 4th inning and another quick hook from Joe to go to his bullpen. In terms of the souring analogy, Whitley has rapidly gone way past his expiration date as a starter. If the Yankees are to have even the slightest chance of contending for a Wild Card spot, they cannot allow him to continue as part of the rotation in the second half.
It's not that he's been bad in those last 4 starts. It's that he hasn't even been competitive. The 8 runs against Toronto came on 11 hits and 3 walks. That's more hits allowed than outs recorded. He put 10 baserunners on against Boston, and he's put 40 total on (32 hits, 8 BB) in a mere 14 IP over those 4 starts. After failing to surrender a home run in his first 5 starts and giving up only 1 in his first 7, Whitley has allowed 5 in his last 4. After giving up 4 BB in his first 7, he's handed out 8 in his last 4. Those numbers are not indicative of a pitcher who's just missing his spots and getting burned by some bad BIP luck. That's a guy who's lost his command and is getting tuned up and taken behind the woodshed by Major League hitters as a result.
This kind of performance wouldn't be acceptable if the starter in question was providing some decent length in his starts. That Whitley isn't coming close to doing that only makes it more necessary to get him out of the mix. He hasn't recorded a single out in the 5th inning of a start in almost 4 weeks. With all these injuries, the Yankees are no longer equipped to make up for that kind of 1-game bullpen strain with the rest of their rotation. Hiroki Kuroda has been inconsistent and more inefficient with his pitches than we've seen in the past, David Phelps is even more inefficient than that, Brandon McCarthy puts a lot of guys on base, and Shane Greene is still in the honeymoon phase of his MLB career. There are guys there who can go 6 or 7 innings, but nobody that Joe can give the ball to and realistically count on for 8+ if he needed to.
Because of that, all the extra stress from Whitley's short outings have been put on the bullpen and the cracks in that middle relief group are starting to show. Adam Warren's become much more hittable since the start of June, Dellin Betances is still getting used heavily, David Huff has had to start pitching more important late-game innings, and the cycle of extra arms coming up from Triple-A solely so that Joe has another one he can use is almost constant. The Yankees are 1-3 in Whitley's last 4 starts and 0-3 in the 3 games after those starts, primarily because they've had to use their lesser relievers in close late-game situations in those games. They can't continue to operate like this for another 70 games and survive. They need to lighten the load and put some more back on their rotation, and the easiest way to do that is to replace Whitley.
With whom to replace him, you ask? No clue and honestly no preference. Maybe recent addition Jeff Francis. Maybe Chris Leroux, who's returned from injury and stretched back out in Triple-A. Maybe Bryan Mitchell eventually, even though he was sent back down yesterday, simply because he's already on the 40-man. Whoever it is, it needs to be somebody because Whitley isn't even in the condiments section of the grocery store let alone cutting the mustard anymore. He gave the team some stability for a while and it was fun to watch him pitch well, but he's been exposed as being in way over his head at this level and at 81 IP on the year between Triple-A and the Majors he's almost reached his career high already.
He doesn't have to go away altogether either. I think Whitley could be very valuable as a righty middle reliever. That's the role in which he's spent the bulk of his career and he's had success in it as a single and multiple-inning pitcher. The one appearance he made after getting bumped from the rotation was a scoreless 2-inning outing against the Indians last Wednesday in which he didn't walk a batter, struck out 3, and picked up the win. Whitley can definitely still serve a meaningful purpose to the Major League club in the second half. For the sake of the bullpen arms and the team's chances of winning balllgames, he cannot continue to serve as a starter.