CHICAGO -- Carlos Marmol has given up more runs in 10 games this month than he did in April and May combined, and that's not good.

The Cubs reliever, who led the National League in stranding inherited runners last season, had an extra film session on Sunday with pitching coach Larry Rothschild and bullpen coach Lester Strode. Marmol has walked five and hit two batters in his last two outings, and given up eight earned runs over eight innings this month, compared to seven runs over 34 2/3 innings in the first two months.

"I think it's just a question of release points," Cubs manager Lou Piniella said of Marmol's recent problems. "Plus, I think he was too crouched spinning out of his delivery, so I think you'll see him a little taller so he can drive down as opposed to coming up. Those were the conclusions."

Marmol agreed.

"I was looking at what I did wrong, and what I was doing good," Marmol said of the session. "I think I can fix it -- no, I don't 'think.' I'm going to fix it."

Speaking of pitching, left-hander Sean Marshall threw on the side for Rothschild before Sunday's game, and then left the ballpark. Marshall was slated to start Tuesday in the Cubs' Interleague opener against the Baltimore Orioles. He has been pitching at Triple-A Iowa, and was 1-1 with a 3.41 ERA in seven games, striking out 25 over 31 2/3 innings.

In his last start Thursday against New Orleans, Marshall gave up one run on four hits over eight innings and struck out four. It was his longest outing of the season.

"He's about as stretched out as stretched out can be," Piniella said.