While i'm inclined to agree with much of what you say, and even that Mika and Davis had deficiencies on D, it's quite clear to me that the mere presence of Mika and Davis enhanced the defense more than the CB experts think. That effect might have been more a result of them inhibiting shots at the rim than their physical play to prevent a low post pass.

Pomeroy data is so clear on this stuff that average height is correlated to good defense. And BYU defensive PPP numbers also correlate to average height, knowledgeability and physical play of players notwithstanding: 3 years ago, BYU had its best adjusted offensive PPP under Rose, and his poorest defense PPP. This was a direct result of the playing small. Defense has improved in the subsequent 2 years with more legit bigs, but that was more than offset as the offense has fallen off a cliff.

Regarding Luke, i think his leadership value is essential with this group and he is worth a roster spot, imo.