The reason was Tuesday's's MRI on Santana's ailing back. The Mets refused to elaborate on Santana's health, other than to have Terry Collins explain Tuesday night after the 6-2 loss to the Rockies that the doctors had yet to read the MRI and planned to do so Wednesday morning.
But based on the delayed update, it is looking more and more as if what was initially described Monday as a minor back ailment will end Santana's season. After the game, the team announced that Collin McHugh will be added to the taxi squad Wednesday, with the plan to have him start or be in the bullpen Thursday.
If Santana is shut down, that would be a dizzying turn of events. A day earlier, the Mets cleared him to start Thursday against the Rockies. Santana threw a scheduled bullpen session Monday and confirmed he was fit enough to pitch, despite a 15.63 ERA in his last five starts.
But a few hours later, Santana's stiff back became more of a concern, and the team's medical staff recommended an MRI. Santana may have done further damage to his back with his side throwing session, but he provided no indication of that.
"We've been very careful and made sure everything is fine," Santana said after Monday's workout. "But to say that you pitch without any pain or any problems, I don't know any pitcher or anybody that can say that nothing's bothering him. It's part of the game. It's what we do and we adjust to it."
Now the Mets must adjust to what is expected to be another prolonged absence by Santana. McHugh, 25, is 7-9 with a 2.88 ERA in 24 starts, 12 each at Triple-A Buffalo and Double-A Binghamton. On Saturday, he threw seven scoreless innings against Pawtucket.
As for Santana, it's time to think about next season, the final one of his six-year, $137.5-million deal. The Mets owe him $31 million for 2013, and it wouldn't hurt to have him well rested.
In a sense, this season was like an extended rehab session for Santana, who worked his way up to pitching every five days before throwing the franchise's first no-hitter June 1. The Mets may never fully comprehend how much that 134-pitch effort drained him, especially after not pitching in 2011. He also did his best to downplay the severity of a sprained ankle suffered July 6.
The Mets finally put him on the disabled list July 21. The official reason was the ankle, but general fatigue was a likely factor. It took a while for Santana to admit he needed a breather.
"Because he's pitched enough years with discomfort," Collins said, "be it his knee, his elbow, his shoulder . . . he's come to realize the importance of making sure he speaks up. He's realized he's got to be smart enough to know that ultimately, it hurts us and him because it's going to mean a lot of time down."
After five years, Santana is 46-34 with a 3.18 ERA in 109 starts for the Mets. The only season he made 30 starts was 2008 (34), and the Mets say they are satisfied he was able to log 21 this year after a long absence.
"I think that's pretty good," Collins said before the game. "He's got to be very happy that he got that far."