The Astros recalled Delgado from Triple-A Sugar Land on Thursday.
The Astros designated Velazquez for assignment Thursday.
Walker isn't in the lineup for Thursday's game against the Angels, Chandler Rome of The Athletic reports.
Diaz isn't in the lineup for Thursday's game against the Angels, Chandler Rome of The Athletic reports.
Pecko allowed two runs on three hits, three walks and a hit batsman while striking out four over 3.2 innings in a no-decision versus the Angels on Wednesday.
Vazquez went 1-for-2 with a solo home run and a walk in Wednesday's 3-2 win over the Angels.
Hader walked one and struck out none in a scoreless and hitless inning to earn the save in Wednesday's 3-2 win over the Angels.
Rocker (4-10) took the loss Wednesday against the Nationals, allowing two runs on six hits and a walk while striking out three over five innings.
Pena was removed from Wednesday's game against the Angels due to a right hand contusion, Matt Kawahara of the Houston Chronicle reports.
Jansen is out of the lineup for Wednesday's game against the Nationals.
