Playing with a hairline fracture in a left rib, Ramirez was a combined 0 for 6 in Games 4 and 5 of the National League Championship Series. He played six innings in both games.
"If he says, 'Oh, I'll go out there, but I don't feel like I can do anything,' then we're going to have to make a decision," Mattingly said on a conference call with reporters. "He's got to be able to feel like he can do something."
Ramirez was injured when he was struck by a Joe Kelly fastball in Game 1. If he can't play Friday in Game 6 at Busch Stadium, the Dodgers would turn to utilityman Nick Punto, who made 44 appearances at shortstop during the regular season.
In the NLCS, Ramirez missed only Game 2. He played the first eight innings of Game 3, in which he was two for four.
"We don't feel like he's getting any worse," Mattingly said.
If anything, Mattingly felt Ramirez looked better at the plate in Game 5 than he did in Game 4, when he struck out three times.
"I thought he had a couple of swings that looked more like himself," Mattingly said. "Obviously, not a 100% like himself, but better. He's just going to have to be honest with us. I don't need a hero from the standpoint that, 'I can go out there but I know I'm not going to be able to do anything.' "
Mattingly thought Ramirez would benefit from the time off between Games 5 and 6. Game 5, which was played at Dodger Stadium, started at 1 p.m. Game 6 is scheduled for 5:30 p.m. PDT.
"He has most of the end of the day yesterday, all day today and pretty much all day tomorrow," Mattingly said. "So it's almost three days. I'm hoping this gives him a little bit of relief. But I do think it's something that until he stops actually trying to swing a bat and twist and things like that, this thing's not going to fully heal."
Mattingly sounded more certain about the status of Andre Ethier, who has played the last three games with what appears to be a microfracture in his lower left leg.
"Andre, I expect to play," Mattingly said. "I think he felt probably as good yesterday as he's felt since coming back. He just seems to get a little bit stronger as far as being out on the field."
Mattingly decided against replacing Ethier in center field late in Game 5. "We were comfortable with what we were seeing, and he was comfortable also," Mattingly said.
Even though Ethier misplayed a ball off the top of the wall, which resulted in a third-inning triple for Carlos Beltran, he said that had nothing to do with his injury. "Just slipped," Ethier said.
Ethier later ran down a couple of balls in the right-center field gap. "I trust I can do the whole thing again," he said.
The Dodgers claimed outfielder Mike Baxter from the New York Mets. To create a place for Baxter on the 40-man roster, the Dodgers designated Alex Castellanos for assignment. Baxter, 28, has appeared in 194 major league games, hitting .229 with 22 doubles, four home runs and 26 runs batted in. He made his major league debut with the San Diego Padres in 2010.