NEW YORK -- Though Mets manager Jerry Manuel recently reneged on his proclamation that Jason Bay may be done for the year, so far there have been no indications to the contrary.

Mets doctors still have not cleared Bay, on the disabled list with a concussion since July 26, to participate in baseball activities. Until they do, he cannot even begin to work toward a return.

"The basic situation is it's in the hands of the doctors," general manager Omar Minaya said. "Right now, he hasn't been cleared to do baseball activities at all."

Bay was batting .259 with six home runs and 47 RBIs in 95 games before the concussion, in the first season of a four-year, $66 million free-agent contract.

Day after walk-off, Castillo back on bench

NEW YORK -- Balancing the desire to win now against the goal of building for the future has not been easy for the Mets -- particularly not for manager Jerry Manuel, who likes to reward his players for their successes.

In another situation, Manuel might have played Luis Castillo on Wednesday, one day after the second baseman hit a walk-off single in a victory over the Marlins.

Instead, Castillo was back on the bench, playing backup to 20-year-old rookie Ruben Tejada -- who went 0-for-2 in Wednesday's 5-4 loss and is batting .167.

"It might not be the situation that he likes," Manuel said of Castillo, who walked as a pinch-hitter Wednesday. "But it's a situation that he'll have to adjust to."

Though Castillo has not been blatantly critical of his manager, he has grumbled his disapproval in the two weeks since the Mets named Tejada the starter at second base. And he has reason for his scorn. At a time when the Mets insist they remain in a pennant race, Castillo has proven capable of providing them with superior offense and -- at the very least -- comparable defense.

The club has acknowledged the former point, but not the latter.

"It would be difficult to sit here and say that [Tejada's] a better offensive player than Luis at this point," Manuel said. "I would have to agree with that. And you have to weigh, what do you like best, the defense or the offense?"

But Tejada's ultimate zone rating -- a statistic that broadly measures a player's defensive range and prowess -- is actually negative at second base, intimating that, so far this season, he has been a below-average fielder at his new position. Tejada has made four errors in 46 games, three of them in 32 games at second.

Castillo, who has made just one error in 63 games, has an above-average ultimate zone rating. And he has consistently been significantly better with the bat.

"Offensively, he's struggled," Manuel said of Tejada. "There's no secret of that. But I do think and believe that he's going to become a good offensive player. Not a great offensive player. But I think he's going to be able to hit at this level."

At the very least, the Mets are willing to sacrifice production down the stretch to find out.

"When you have a young kid," general manager Omar Minaya said, "you always like to give a young kid an opportunity to play."

Martinez on DL at Triple-A Buffalo

NEW YORK -- Three days after aggravating his surgically repaired right knee in a game at Triple-A Buffalo, outfielder Fernando Martinez landed on Buffalo's seven-day disabled list with right knee soreness.

Martinez, 21, was batting .253 for Buffalo but .367 over his last nine games, recently earning a brief callup to the Mets. Though Martinez was a likely candidate to return when rosters expand Sept. 1, his injury may delay that move.

The Mets have not announced their intentions for September callups, though right-handed pitchers Jenrry Mejia and Sean Green, left-hander Raul Valdes and utility man Nick Evans rank among the most likely candidates for promotion.

Club not worried about Niese's innings total

NEW YORK -- The Mets have discussed the possibility of an innings limit for Jon Niese. For now, though, they are opting to ignore it.

One day after manager Jerry Manuel shrugged away the notion of an innings limit for Niese, general manager Omar Minaya acknowledged that an organizational discussion took place Tuesday -- but that the Mets won't be taking any imminent action regarding their 23-year-old left-hander.

"When you get to September, you talk about all those kind of things as far as innings and all that, but there is nothing going on like that right now," Minaya said. "We had a conversation and we feel pretty good about where he's at."

With roughly eight starts remaining, Niese has pitched 138 innings -- 18 more than he threw during an injury-shortened 2009 season. But Niese is just two years removed from throwing a career-high 180 innings over three levels in '08.