Brocail will instead become a special assistant and probably become one of the roaming minor league instructors Houston rolled out this season.
The Houston Chronicle's Jose Ortiz hinted at moves days ago and none of these are surprising. His characterization of Brocail of a "highly respected member of the Astros family since his days as a fiery reliever," however was surprising. Brocail may have pitched for Houston twice, but he pitched more years for San Diego than the Astros and spend just as much time in Detroit as he did in Houston. Plus, Brocail has been working for Houston for how long now and this is the first time he's been described as "highly respected?"
Be that as it may, many Astros observers were surprised when the team didn't reassign Brocail after last season, when the pitching staff again struggled. In the offseason, Jeff Luhnow discussed that and said Brocail had the potential to be a top-flight pitching coach. Bringing in Dennis Martinez was supposed to give Brocail a little more experience to lean upon, but that didn't work out, as the bullpen devolved and none of the young pitchers on the entire staff took a step forward in the majors.
Start speculating on replacements in the comments. I have to think that Vince Coleman, already a special assistant in the minors who specializes in base running and the outfield, fits Clark's roles perfectly, since Clark was in charge of the major league baserunning and outfield.
If I were forced to throw out names who might replace Brocail as pitching coach, I would instead look to successful organizations which fit Houston's analytic style. I wouldn't be shocked if the Astros went after someone from the Rays, the A's or, of course, the Cardinals.