JMG is a dumpster and had 7 minutes (-2+/-)
JaMychal was solid in his first stint: knocked down his shots, crashed the glass and made a number of good defensive plays (forcing FVV into a turnover on the perimeter is beyond Wiseman's capabilities, at the moment).
In general, he makes less mistakes on both ends, and most importantly, the Warriors don't need to abandon the system when he's on the floor. Whatever you think of him, Wiseman is notably worse for the functionality of this squad. That's why the coaching staff trust him more.
Ideally, no contender should be deciding between playing JaMychal or Wiseman in the first place.