I think Coach L gave Walker the chance to win that fifth starter job and he failed the audition. I say that because I'm sure Coach L realized we are a small team overall and a 6'9, athletic player was preferable to a 6'5 athlete.
Unfortunately, Walker still features a game far different than what his height and athleticism would seem to dictate. We don't need him jacking outside shots; we need him to defend and rebound inside. Apparently, those skills are not in his wheelhouse.
Like it or not, Walker is still a key cog on this year's team. As we saw in the UNC game, if Omier gets saddled with fouls, Walker is his "replacement." He played OK in that role so ... we can hope.