The two teams open a two-game series Monday in Philadelphia.
Blanton can be a free agent at the end of the season and that wasn't a particularly happy thought after his first four appearances (three starts) of the season.
He was 1-3 with a 4.34 ERA.
Since then, he's shown signs of being all the way back from the elbow issues that plagued him in 2010 and 2011. In his past three starts he's 2-1, with a 2.35 ERA.
In those three outings he's held opponents to a .195 batting average and has struck out 21 batters in 23 innings while walking just three.
There's no real explanation for the turnaround, according to Blanton.
"Coincidence," he said with a shrug. "I threw really well in my first start of the year. I just had two starts on the road that weren't as good. I don't think you can base anything on that.
"I've felt good all year. I've generally been like that my whole career, a little bit of a slow starter. I'm one of those guys who feels a little more comfortable as the season goes on, anyway. The more starts I get, the better I start getting into a rhythm."
The numbers back Blanton up. For his career, he has a .459 winning percentage (39-46) and a 4.59 ERA before the All-Star break. In the second half he's 37-19 (.661) with a 3.88 ERA.
Before Sunday's 3-2 loss in 12 innings at Pittsburgh, the Astros' 6-4 record in May was tops in the NL Central Division for the month.
Unfortunately for them, the recent good streak came after they were 9-14 in April.
The Astros are succeeding on the strength of an opportunistic offense, ranking fifth in the National League in runs scored, and a shut-down bullpen.
Prior to Sunday's games, the Astros bullpen had an ERA of 2.62, second in the NL to the Reds' 2.41.
Closer Brett Myers has led the way, going 9-for-9 in save chances before blowing one Sunday against the Pirates.
"There's a lot of good arms down there," Astros manager Brad Mills said of his bullpen. "A lot of good guys, a lot of good pitchers and they're working well together. There's a lot of confidence from everybody that they're doing a great job."
Astros: Harrell to oppose Blanton
Opposing Blanton on the mound will be right-hander Lucas Harrell, who is 2-2 with a 4.58 ERA. He did not factor into the decision in his last outing, pitching 5 1/3 innings and giving up six hits and two earned runs in a 5-3 12-inning loss to Miami on Wednesday.
Phillies: Rollins starts it off right
Shortstop Jimmy Rollins hit the 38th leadoff home run of his career in Sunday's victory over the Padres. It was Rollins' first home run of the season.
Second baseman Jose Altuve was held out of the starting lineup Sunday, but Mills wound up using Altuve in the 12th inning. Altuve has earned the rest.
He has played in 33 of the club's first 34 games, and was tied for second in the NL in multi-hit games (15), eighth in hits (41) and 13th in hitting at .323, which ranks him tied for second among all Major League second basemen.
It's expected Altuve will be back in the starting lineup Monday.