Several things to unpack here.
Sears was able to take that many shots for multiple reasons;
- College basketball rules and officiating allow for guys to get open. It's hard to fight thru a screen without being called for a foul yet they regularly let guys like Sears push off to create space.
- Sears is similar to Carsen Edwards in that he doesn't need much room to get his shot off
- Purdue by nature of having a 7'4, 300 pound center is susceptible to teams who screen heavily
- Purdue lacks athleticism at the guard position outside of Jones (who is good) and Colvin (who is still learning how to defend at this level)
- Nate Oats is among the best in the game to generate threes and layups. He abhors anything else offensively. Alabama is 6th nationally in 3P% and 26th in 3PA/FGA. It's what they do.
And yes, Loyer is not a great defender and likely never will be. That said, he's 10 games into his sophomore season so it's not out of the question that he can improve to be at lease serviceable. Ryan Cline did and they are similarly built and started from a simiar point.
As for Loyer's contribution on offense when he's not shooting, he is absolutely a focal point of opposing coaches scouting reports. If you watch off the ball when Smith and Edey are playing their two man game, it is rare that defenders cheat off of Loyer. That creates space for Smith to work and do his magic. If his man cheated off of him the way opposing 4 men do, he'd likely be shooting a lot more and a better percentage (and his 3P% is fine at 36% on 4 attempts per game).