It's not that Boston's bench underperformed last year. In fact, the unit's plus-minus rating (+522) was the best by any bench in the NBA. But simply out-performing opponents' reserves wasn't good enough for the Celtics. Boston's backups needed to alleviate the starters' workload – a unit that averaged 166.8 minutes per game (ninth highest in the NBA). If the 'Big 3' are to be fresh come playoff time – particularly Kevin Garnett – the reserves need to play more than their cumulative 75.6 minutes per game from a season ago.
TheHoopsWorld article later noted that Rasheed Wallace used only 11% of his 10.9 field goals per game in the paint. I'd say it looks like we'll have a repeat of that performance this year.