Here is my take on this year's game. I assume that Swanigan and Maker go elsewhere and we play with the rosters as they stand.
In general, freshmen bigs have the same set of weaknesses. First, in high school they are used to being one of the bigger men on the court, and that changes radically in college. They are used to playing against less skilled or smaller people, and have not developed all their skills. Often thier offensive game lacks craftiness. (Zeller, practicing all his life against his older brothers did not have this problem).
Second, they tend to foul while defending, a lot! They have not been coached on footwork, in detail, the way colleges coach their bigs, and they now face opponents with much more sophisticated games. Furthermore, they have not faced the kind of offensive player they will see every game in the BIG.
Third, they lack endurance. The bigs run the furthest in any game (end line to end line), and need the most endurance of all the players. They hit the "freshman wall" about 2/3's of the way through the year. I think Mathias, Haas and Edwards hit that wall last year. It affected their games at the end of the season. I expect that to be solved this year, and I think it accounts for much of the jump from year 1 to year 2 performance.
Purdue's freshmen, next year, will not have to face these problems, for the most part, because there are already strong people in each position who can start. The freshmen can work into the game early, and easily. Doing so without impacting the W-L record. Bryant, on the other hand, will face all of these challenges, and I think he will be prone to fouling on defense. His learning curve will be steep, and may adversely affect IU's W-L record.
When it come down to the IU-Purdue game, I think IU will be in trouble this year. Purdue will pound it inside and get Bryant in foul trouble early. The loss of HP will be more important than most IU guys think. He had experience and he had the physical ability to play in the BIG. Even if Bryant starts, HP would have been first off the bench. His departure really puts IU at a disadvantage in their rivalry game, because this has made IU weaker where Purdue already had the advantage, and where Purdue has a tendancy to go. If you can;t stop your opponent, then you have got to outscore them.
Purdue will likely put the same tight man-to-man on IU's guards to force them to play full out all game, thus creating a fatigue issue. IU's guards will need to do lots of side-to-side movement to get clear shots over Purdue's taller guards. IU can screen to clear Yogi and JBJ, but so far I have not been impressed with that aspect of Crean's teams. If Yogi and JBJ have a statistically normal game against Purdue, IU will lose.
IU will need to hit 3-pt shots at a high percentage, throughout the game, ...and run, ...run every time they have the ball. Maybe Purdue will be slow getting back on defense that game, and IU can get easy baskets. IU can win, but only if Purdue plays at less than their normal capability. On the other hand, this game now has the potential to be a blow out, if Purdue comes in motivated.