MIAMI - After missing most of the first month of the season while serving a suspension, Carlos Ruiz might miss another month because of an injury. The All-Star catcher had an MRI exam yesterday that revealed a Grade 2 right hamstring strain.

Ruiz, who will be placed on the disabled list before tonight's game in Miami, is expected to miss 3 to 4 weeks.

Ruiz left Sunday's game against the Reds after he was hurt running the bases in the second inning.

First baseman Ryan Howard also had an MRI yesterday in Philadelphia. But, unlike Ruiz, there's quite a bit of uncertainty regarding Howard's left knee, which kept him out of his second straight game last night. Team athletic trainer Scott Sheridan said Howard's MRI "concerned" the Phillies.

"He's got some changes in his meniscus and his knee," Sheridan said. "And he's also got some inflammation in the knee that concerns us."

Howard is officially listed as day-to-day. He had a cortisone shot on Sunday.

"The goal is to make him better and be done with it," Sheridan said. "But I don't know if that's going to happen. We're going to do the treatment that we did and see how he responds to it. And then we'll have to make decisions from there as to what needs to be done beyond that."

Howard was unavailable for comment before last night's game. He joined the team late in the afternoon after flying in from Philadelphia.

Howard, 33, is in the second year of a 5-year, $125 million contract. The current ailment involves the same leg that cost Howard most of the 2012 season following Achilles' surgery.

Although the Achilles' is healed, Howard hasn't run well this season. It's worth wondering whether the injuries could be related.

"That's the million-dollar question right there," Sheridan said. "For me, it's like the old song: The foot bone is connected to the knee bone. To me, the closed chain of the ankle relates to the knee, relates to the hip. They all play a part. So that's a reasonable question. Whether that's what's happened, we don't know."

Sheridan said there were "changes" in Howard's meniscus, but when asked whether it was more of a case of inflammation or a tear, the team's chief trainer said it was "a little bit of both."

"When you look at the meniscus, you want to know if there is a tear or anything there," Sheridan said. "Again, there were some changes around the meniscus. Whether that's what's causing the symptoms [we don't know]. When you do an MRI, it's not always nice and black and white where everything matches up to the up, so, again, he has some symptoms that don't match the picture as well as we want. We're just going to have to see where it goes."

Howard is hitting .245 with a .282 OBP and a .713 OPS in 41 games this season - the latter two numbers are both lower than his career-worst numbers in 71 games last season. He has hit six homers and struck out 46 times in 163 plate appearances.

Howard said Sunday that the knee has been an issue since spring training; Sheridan said the pain intensified over the weekend. In the coming days, the Phils will cross their fingers that the cortisone shot kicks in and heals Howard, who is owed a guaranteed $85 million after this season.

"You never know what's going to happen," assistant general manager Scott Proefrock said of the contract. "Injuries are part of the game. That comes with the territory when you sign these guys. We have a bunch of pitchers on long-term contracts, too. It's just the risk you take."

Adams placed on DL

With a laundry list of injuries, the only roster move the Phils made yesterday involved Mike Adams. The setup man was placed on the 15-day disabled list with a right back strain.

Before last night's game, Adams said he was "feeling good." But since he hasn't pitched since May 10, Adams is headed to Clearwater, Fla., to get his arm in gear.

"There's no way I could be ready to pitch tomorrow or Wednesday," said Adams, who is expected to throw in Clearwater on Thursday and Saturday.

Adams' move to the DL was retroactive to May 11, meaning he could be activated as soon as Sunday. He said the plan was to rejoin the Phillies on Monday in Boston.

Catcher Humberto Quintero was activated to take Adams' place on the active roster.

Phillers

Despite losing Carlos Ruiz for the second time this season, the Phils are not looking to add catching depth, according to Scott Proefrock. "I think we're comfortable with what we have," the assistant GM said of Quintero and Erik Kratz. Top catching prospect Tommy Joseph (Triple A) has been out for 2 weeks with a concussion, while fellow prospect Sebastian Valle (Double A) is hitting .211 with a .615 OPS . . . The Phillies will activate Tyler Cloyd before his start tonight. He will take Ruiz' place on the roster . . . According to the Elias Sports Bureau, before Sunday the Phillies hadn't hit back-to-back home runs capped by a walkoff homer since they did it against the Cardinals at the Baker Bowl on Sept. 15, 1922. Butch Henline's third home run of the game tied the score at 9-9 in the bottom of the ninth, while Cliff Lee followed Henline with a game-ending homer. Yes, a different Cliff Lee . . . Lefthander Adam Morgan was scratched from his start at Triple A Lehigh Valley with a shoulder injury. Morgan, 23, is 1-4 with a 4.97 ERA in eight starts with the IronPigs. Morgan has a 7.94 ERA in his last five starts.