Teague just seems to me like one of those guys who might not show much in the regular season, but come postseason his veteran experience comes in handy and he'll make some plays. He's obviously not the flashiest player anymore and is past his All-Star days, but I just have a gut feeling he'll help off the bench come postseason. 
Might also be a little Kemba insurance if he gets hurt again or something. I like Pritchard and he's above Teague in the depth chart, but sometimes in the playoffs that veteran experience and decision-making matters. To be honest it's not like we're expecting Edwards/Green/Waters to contribute much either in the playoffs (although it'd be nice!) and unless you can find a cheap upgrade, you're better off keeping Teague around.