Blanton, who said he planned to watch video Wednesday to confirm his feeling, was unavailable for comment. Dubee said he watched some film and could not agree with Blanton's initial assessment.
In the clubhouse after Tuesday's game, Blanton referenced an issue he had pitching from the stretch in 2009, when he noticed his feet were too close to each other, thus disrupting his arm path. He said he believed that was his problem in the first two starts of this season.
"It's kind of obvious," said Blanton, who allowed five runs in six innings. "I've given up a lot of hits with runners on. I need to make an adjustment there. It's not mind-set or anything. It's the physical execution of being in the stretch."
Blanton added: "I remember that same feeling."
In 2009, when Blanton had a 7.11 ERA after his first eight starts, both Dubee and he independently watched video and spotted the same problem from out of the stretch.
This time, Dubee found nothing. He said Blanton's stuff and velocity are fine.
So what is the problem?
"He's just allowed innings to snowball," Dubee said.
Dubee cited two pitches in the three-run fourth inning he thought were especially egregious - an 0-1 slider to Jayson Werth over the heart of the plate that was hit for a double to lead off, and an 0-1 sinker to Jerry Hairston that was also down the middle and hit for a run-scoring single.
"Those are bad mistakes," Dubee said. "He's not executing."
Dubee said they will be addressed during Blanton's bullpen session Thursday.
With runners on base, opposing hitters are 9 for 18 against Blanton with three walks and three strikeouts. With the bases empty, hitters are 8 for 27 (.296) with no walks and seven strikeouts.
Blanton's next start will come Sunday at Citizens Bank Park against the Florida Marlins.
Bullpen's streak ends
Both David Herndon and Danys Baez allowed runs out of the bullpen Tuesday, ending a 191/3-inning scoreless streak for the team's relievers. That streak was the team's longest since 2004 (28 innings).
Still, entering Wednesday, the bullpen had a major-league leading 1.93 ERA. It has been done without the frequent use of Ryan Madson and Jose Contreras, both used in just three of the season's first 10 games.
The Phillies will miss Josh Johnson this weekend when the Marlins visit. Johnson did not allow an earned run to the Phillies in two starts (15 innings) last season. . . . Cliff Lee starts the finale of the three-game series against the Nationals on Thursday. The last time he pitched against Washington, he twirled a shutout on Sept. 15, 2009.