He'd be a Ukrainian John Ruiz with more punching power. He'd have considerably less success since his height and reach were the foundation for his tactics. If he fought in the 80's or 90's he could probably pick up a strap, but in his own era he wouldn't make it that far and Vitali would be the consensus #1 guy (unless he also get shorter somehow).
Probably not nearly as well. While there is certainly a lot more to Wladimir Klitschko’s success than just “ size “ it was certainly a big factor
I agree that Wlad without the size would be a lot less scary. He really learned how to maximize his dimensions and guys that were significantly smaller than him were almost universally SOL. His jab was a multifaceted weapon and it really became great because of his reach and stance. That said if Wlad were smaller he might gain other attributes which could help compensate for the lack of dimensions. He was a fast heavyweight for his size - if he were much smaller he might gain a lot more speed. That in itself would be interesting since he was an offensive machine before Purrity, Brewster and Sanders persuaded him not to trade punches as a first strategy.
He woudl need to radically change his style, but I believe that he could still enjoy success. His style masked a bit of artistry.
What are the rules of this game? - Do we shrink prime Wlad down to 6'1" - and see if he could dominate the CWs? - Or do we shrink him down to 6'1" - and match this version against the big boys at HW?