Honestly, the biggest switch for this team happens on the boards, mainly from Pierce and Rondo.
Pierce and Rondo are two of the best rebounders for their position. Couple that with KG and Shaq/JO and the Celtics have the best rebounding team imo.
Unfortunately, this doesn't happen except for teams like Miami or San Antonio, or obviously during the playoffs.
But honestly, the entire team has that switch, even KG. The switch is not lack of motivation. It's fear of getting injured over putting in an extra 20% of effort. If the Celtics went 120% on the court for 82 games, they could win 65 games but would be absolute toast at the age they are at.