I like the on-court/off-court stat.  It's kind of the cousin of the plus-minus, and has some similar flaws (with whom you did you play and play against?)

Still, it's pretty positive for Al: 


Overall offense rating is +6.7 which is a pretty massive number.  

Al played on a pretty bad team, so his box plus minus compared to an average team puts his slightly above replacement value.  But, watching him I'm sure that is an underestimate of his talent and the on-court off-court stat is a better representation.