It wouldn't have hurt him, but Whitaker and Sandberg had very different careers. Sandberg was a high peak performer whereas Whitaker never had an MVP type year. Whitaker had a longer career and had more good years than pretty much any middle infielder ever, but never had a great year. The voters appear to favor peak years (and it doesn't have to be a lot of them) over career. On the other hand, Whitaker was a private person who didn't get a lot of publicity, so he might have benefitted from more national exposure, but I think his unusual career arc hurt him him more than anything. Calendar years are arbitrary cutoffs, but it's what people look at.