I am not that big a fan of Lawrence Frank.
I always thought his NJ teams lacked an identity. That they didn't have a firm style of play, an ethos ... an understanding of what they needed to do with their personnel to win games and play the type of basketball that leads to titles (and their two runs to the Finals) with a discipline to achieving those goals ... they were too loose with their play, team wise. The stars there just did what they felt like. Not enough direction, big picture wise.
That said, I thought Frank did a great job with his in game coaching though. Choosing effective lineups and figuring out the best way to matchup against their opponent. Creating and eliminating matchup advantages. Getting good combinations, players who worked well alongside one another, on the court together. Good use of timeouts. Nice plays out of timeouts. Very good Xs and Os guy. Great preparation before games, game to game, got his team ready for their opponent. Good motivator in this area too.
So long as he didn't try to change anything too much here ... Frank could probably do a good job coaching the Big Three and Rondo if Doc chose to leave this summer.
I wouldn't want him here beyond that point though. Not convinced about that other stuff, the stuff Phil Jackson does so well (and that Doc has done so well). Once the roster starts to change and the Big Three depart, I would be concerned about Frank's ability to lead the team going forward.