Current global snapshot: Tier S, 49.30% win rate, 1.79% pick rate, 0.26% ban rate.
Marco Polo is picked for mobility and true damage pressure, but he is not a free escape button. Chain Reaction rewards repeated hits, which means spacing and bullet accuracy matter more than raw item gold. A good Marco wins long fights by stacking passive and choosing the right dash angle. A bad Marco dashes forward and gets stunned before Fevered Barrage finishes.