Even if there were zero tangible results of Rondo helping the team, having a player with his experience and acumen is absolutely invaluable for a guy like Garland's development.
I listened to Jared Dudley talk reverently about how much of a savant Rondo was, and he focused on their film sessions to illustrate his point. The way Rondo would break the game down and point things out that nobody else could floored him, and Dudley up to that point had been doing this A LONG TIME.
So even if the Rondo acquisition ends up looking like a giant "meh" when it comes to its effects on this particular season, I'm confident that it will overall positively impact Garland's approach to the game.