Between Billy Williams in 1987 and Gary Carter in 2003, no one who had gotten less than 50% of the vote in a given year had eventually gone on to be elected to the Hall by the BBWAA. Since then, Ryne Sandberg made it after getting 49% in his first year; Bruce Sutter made it without even cracking 1/3 of the vote in his first six years on the ballot; Goose Gossage got 33% in his first year and below 50% each of his first five years; Jim Rice started out below 30% and had 5 years under 50%; Andre Dawson started at 45% and then had two season at 50% before making it on his 9th time on the ballot; Bert Blyleven was below 20% his first three years, and below 50% nine times; Tim Raines was under 20% his first two seasons, and under 50% six times; Jeff Bagwell had 42% his first time on the ballot; Mike Mussina started off with 20%, 25%, and 43%; Edgar Martinez was between 25-43% for his first seven times on the ballot; Larry Walker was between 10-23% his first seven times on the ballot.
All those guys are controversial picks - there was a time when a majority of voters passed on them. I think of a few of them as deserving to be in the Hall, but Bagwell is the only one I'd consider much more than a borderline pick. Of the other picks who were elected by the BBWAA during that time, there are very few who people tend to argue against. I'd skip over a few of them myself (Hoffman, Sutton, Fisk), but probably agree with close to 90% of the selections, outside of that group listed above that failed to crack half the ballots during some years.
So tying it back to the guys on the ballot now... Schilling, Clemens, Bonds were under 50% four times each; Vizquel has gone 37-43-53%; Rolen went from 10-17-35%; Billy Wagner, four years between 10-17%; Sheffield had five years under 14%; Todd Helton went from 16%-29%. Even if some of these guys do get voted in, it seems clear that a lot of voters don't really think they deserve it.