Willis a 6'9" player that has attempted 26 free throws for his entire career because he does nothing but camp out on the three point line. In 128 minutes of play this year he has only attempted eight free throws, and that's mostly against inferior competition that he could have easily gotten to the line against.
His average is 0.7 made free throws a game this year. As soon as he gives up one basket to the other player, his free throw contributions (so far this year) are already a negative on the scoreboard. You do realize that he if would do what the team needs him to do (defend and rebound), then all of this would be irrelevant and he would get more playing time. Who cares if he shoots 1000% from the free throw when he's averaging less than one a game? Making less than one free throw a game does not get you playing time over not rebounding and defending.
Defense and rebounding are much, much, much, more important than free throws in a game of possessions. Are you really this clueless about the game that you would give up defense and rebounding for a couple of free throws, especially when said player doesn't even get fouled enough for his free throws to even make a bit of difference?