WASHINGTON -- The selection of ace lefty Cole Hamels as Sunday's starter seems obvious. The Phillies are playing the National League East-leading Mets on ESPN's "Sunday Night Baseball."

The Mets are scheduled to start their ace, lefty Johan Santana. Shouldn't the Phillies counter with Hamels on what would be "normal" rest, or four days off between starts?

Pitching coach Rich Dubee said it's not that simple.

"He could be pitching on four days' rest the rest of the year," Dubee said. "That's something he hasn't done for five starts in a row all year. You have to take that into consideration. I don't think he's had a stretch all season where he's pitched five starts in a row on regular rest ... And he's also sitting on 195 innings right now."

While that may sound like not a big deal, starting pitchers and their handlers crave those built-in "extra" days, when off-days during the regular season allow the members to take an additional day of rest. The lefty has pitched on four days' rest 15 times this season, and received five days' rest 11 times. The All-Star break afforded him six days' rest.

Starting Sunday and then Sept. 12 against Milwaukee would give Hamels four straight starts on four days' rest, something he hasn't done since last season.

Dubee and manager Charlie Manuel are considering Hamels and J.A. Happ. Sunday's starter is listed as "TBA," an indication that it won't be Kyle Kendrick.

"TBA is a [good] starter," Dubee said.

What kind of stuff does he have?

"TBD," he said. "We don't know what he has."

The decision on Hamels will likely come down to how difficult an outing he has against the Nationals, and how his arm responds in the next few days. He declined to pitch the eighth inning Aug. 28 against Chicago, saying he had enough after needing 20 of his 108 pitches to get through the seventh inning.

As for Kendrick, he might receive a brief sabbatical after posting a 9.14 ERA in his past five outings. Three of those starts lasted fewer than five innings. Manuel is most concerned about the righty's "look" on the mound.

"The thing that concerns me about Kyle is he's kind of worked his way to where he's at," Manuel said. "You could kind of see it coming, how he'd address hitters. I've seen him get two hitters out, boom-boom, and then all of a sudden he'd pitch around a guy, and it wasn't necessarily a good hitter. He'd be kind of pitching around him and walking him, then all of a sudden he can't get anyone out. That was the complete opposite of how he pitched before.

"His composure was one of the biggest parts of his pitching last year. If they hit him he'd get back on the mound and throw his sinker. If he made a bad pitch, he'd get right back on the mound."