Dunn only 18 career bWAR. Kyle at 19.7 already. Of course neither gets anything from defense or baserunning. Or probably actually lose points. Schwarber is career 127 OPS+ to 124 for Dunn.
That OPS+ includes Dunn's decline years which Schwarber hasn't experienced yet. Chances are Schwarber's career OPS+ will drop as he ages.
And WAR isn't a good fit for this archetype of player and underrates both in my opinion, but for what it's worth fWAR has Dunn at 25.6 for his career vs Schwarber at 21.2 (nearly a quarter of which is coming from this season alone).
Dunn triple slash (including his decline): .237/.364/.490 (.854)
Schwarber triple slash: .232/.347/.501 (.848)
They're pretty close I think.