Next year he may be first or second in line for minutes at the 4. Why play just a few minutes this year if you can optimize your minutes when Clark and Washington are gone?
I see Clark getting almost 30 minutes per game this year but he will get ZERO next year with no clear incumbent. So a new player can compete with 3 or 4 other players for 10 remaining minutes or he can red shirt and compete for perhaps 30 minutes the following year. Some players have too much EGO to let that happen and some players have the smarts to understand the situation.