How good of a GM was he for the Astros?
Bob Watson, when with the Houston Astros (and then later), had/has a reputation as a good evaluator of young talent. Houston was going to go with young guys for a good long while, so Watson was key with his ability to spot talent and draft well. His weakness is his somewhat stubborn streak and sometimes combative nature. His most famous fight was with, ironically enough, his #1 draft choice Phil Nevin. Nevin was full of himself and wanted to be brought along faster than anyone else thought he should be. He also cause many a riff in the organization. Watson read him the riot act, but Nevin bascially ignored him and said "so what". So Bob Watson got rid of him, and Nevin almost lost his entire career because of it. Nevin bounced around a bit until he reached San Diego and he finally grew up and realized he was to blame for his own career failings.
Later in his career, well after his job with the Yankees and with the Astros, Bob Watson was assigned the job by the MLB of putting together the young Olympic team. Watson scoured the minor leagues for talent and put together what would eventually be the Olympic team that won a gold medal over Cuba. Ben Sheets, Roy Oswalt, Adam Everett, Jon Rauch, Brad Wilkerson, Doug Mankebunchalphabets, Kurt Ainsworth and Brent Abernathy were just a few of the key minor leaguers that Watson put together as a team to go play in Sydney. It is said that Watson came to see Adam Evertt play one day and while there scouting him, he heard of the kid named Roy Oswalt. So he asked permission to come see the kid pitch in AA if Houston didn't mind. He loved what he saw and invited him to join the team.
Watson knows young talent, is good at drafting players but no one really knows if his stubborn, somewhat stern ways works with veterans or not. Young guys may listen to "Mr. Watson" and fear him a bit. Veterans may just ignore him. So if the team is going to be mostly about getting the most out of young talent, Watson is a good choice. If it's a veteran free agent you want to sign up, it may be harder with Watson at the helm.
BTW - this would be Watson's second stint of being a GM under Drayton McLane. McLane was responsible for firing his first GM, Bill Wood, because he convinced the neo owner of the Astros that he should make a splash in the free agent market and sign Doug Drabek and Greg Swindell. When neither panned out, Wood was fired. It was Watson, then the assistant to Wood who got promoted to continue the work with the young club that was going to try and jettison many veteran guys to allow the youngsters a chance to play. BTW - it was Bob Watson who pulled the trigger on the Caminiti to San Diego for Derek Bell trade. He is a no nonsense guy.