Here's a very illuminating and friendly article on Chuck Hayes:
Lots of stuff in there I had no clue of. I will be honest, I don't know if I could have told you that Chuck Hayes was an NBA player before the trade.
"As a junior attending Modesto Christian High School in California, Hayes was named all-league and all-state. That year he grabbed 31 rebounds in the 2000 Northern California championship game - a California High School record for all divisions."
Played four years in Kentucky - "Hayes finished his career at Kentucky ranking 7th all time in rebounds, 8th in steals, 9th in blocked shots and 35th in points."
He went undrafted, spent some time in the D league then "Hayes was signed to a 10-day contract on January 18, 2006. In his second game in a Rockets uniform, Hayes posted a double-double, collecting 12 points and 13 rebounds in a 109–108 double-overtime win over the Chicago Bulls on January 20."
"Hayes was one of the most efficient defensive players in the league, ranking 3rd among rookies in rebounds per 48 minutes (16.1) and 14th in steals per 48 minutes (2.33). He also had an FG% of 52.6%, good for 11th highest in the league among players with at least 100 field goals attempted."
"From 2003 to 2009, Hayes had the second highest defensive adjusted plus-minus of all NBA players."
Maybe this is the reason Casey uses him in close games.