I was curious so I looked it up. Co-Rookies if the Year:
1970 - Geoff Petrie (Portland, #8 pick) and Dave Cowens (Boston, #4)
1995 - Jason Kidd (Dallas, #2) and Grant Hill (Detroit, #3)
2000 - Elton Brand (Chicago, #1) and Steve Francis (Houston, #2)
1958 Rookie of the Year Woody Sauldsberry of Philadelphia was the #60 pick in the 1957 draft, so Casspi wouldn't be the lowest draft pick to win it.