Mookie is leading the NL in OPS (1.020), fWAR (7.5), and wRC+ (174). The stolen base/batting average factor for Acuna, batting average for Freeman, and home run factor for Olson will probably factor in, but Betts should be the front runner right now.
Also, he's looking to hit 40 homers from the leadoff spot, which as never been done in MLB history.