Cabral, 25, faced five batters on Friday night and did not retire any of them, as the Rays swelled their lead from 8-5 to 11-5 during his outing. Cabral allowed a leadoff single to Ben Zobrist, threw a wild pitch and served up a run-scoring single to Brandon Guyer.
Evan Longoria and James Loney were hit by pitches, loading the bases, and Wil Myers delivered a two-run single that struck the third-base bag. Cabral then drilled Logan Forsythe in the back with a pitch, prompting the immediate ejection by West.
"He just clearly has no command; it's unfortunate," Yankees manager Joe Girardi said. "Obviously we're not trying to hit anyone there, and I feel bad that we hit three people there. You've just got to move on and go from there."
Girardi came out of the dugout to argue on behalf of Cabral, who was making his fourth appearance of the season after starting the year with Scranton/Wilkes-Barre, and the manager indicated afterward that he wasn't happy with West's decision to eject Cabral. He also wasn't pleased that he had to further empty out his bullpen and send in right-hander Shawn Kelley.
"You really don't want to," Girardi said. "It's unfortunate that we had to do it."
Cabral said he felt good when pitching to Zobrist but couldn't explain his complete loss of command after that. He said his pitches might have been moving too much, which is why they were "all over the place."
Cabral said West didn't offer a warning at any point, nor did he provide a reason for the ejection.
"Today was not a good day," Cabral said before the announcement that he had been designated for assignment. "I didn't try to hit anybody. I want to throw strikes. That happens sometimes. They know I don't want to hit anybody. I'm surprised because they [didn't] tell me [anything], you know?"
Adam Berry is a reporter for MLB.com. Follow him on Twitter at @adamdberry. Bryan Hoch contributed reporting. This story was not subject to the approval of Major League Baseball or its clubs.