Four spots in the rotation are solidified as of Friday, with Jason Vargas and All-Star Jacob deGrom rounding out the bunch, but there are a number of reasons for expanding the rotation as the team moves forward.
Left-hander Steven Matz remains sidelined with a flexor-pronator strain in his left forearm and, though he was scheduled to only miss one start, he will likely be out for longer. In his place, the team recalled Corey Oswalt on Aug. 3, and the rookie has eased into his role nicely, taking full advantage of the opportunity -- in his last five outings, the right-hander is 1-1 with a 3.81 ERA.
Callaway said he would prefer Oswalt to remain at the big league level, continuing to get his work in while easing the load placed on the team's other starters as the season winds down.
"We have options," Callaway explained. "There are a lot of things we can do. I think we want to see [Oswalt] pitch tomorrow and then sit down and really see exactly what we want to do with all of our players after that."
Oswalt is scheduled to start Sunday against the Marlins, his second straight outing in place of Matz. The rookie lasted just 2 2/3 innings, giving up six earned runs, when he pitched in Miami on June 29.
As for Matz's return from the disabled list, Callaway was confident that the left-hander will be back soon. Barring any setbacks, the club is hoping for Thursday, when the Mets are scheduled to play a doubleheader in Philadelphia.
"He's going to throw a simulated game tomorrow," Callaway said. "Basically, a glorified simulated game against hitters early. He's feeling really good, and we'll see how he comes out of that, and we'll go from there."
When asked about what a six-man rotation would mean for deGrom, Callaway laughed, assuring he would speak to his ace prior to making any decision on the matter.
"We would have a conversation with Jake," Callaway said. "We understand where he's at and what he's trying to do, and we would make sure he's taken care of."
Bruce nearing return to baseball action In other injury news, the long-awaited return of Jay Bruce is drawing closer.
Bruce hasn't played since June 17, when the veteran landed on the disabled list with continued right hip soreness, along with a combination of various ailments.
Callaway said Friday that, although he can't pinpoint the three-time All-Star's precise return date, it's "getting close."
"Jay's doing really good," Callaway said. "He's going to be playing in games very soon, and hopefully we can get him back here and help us out. We're going to have him playing some outfield and playing some first base so that'll be a good option for us at either position."