No, you can't necessarily ignore someone because they have a great year and have never done anything comparable in their career. However, a guy like Schmidt and especially Loaiza is going to be a much higher risk to draft next year, than a pitcher that has been consistently good for a number of years (like Schilling, Hudson, Mulder, Mussina, etc).
You just never really know which one is a one year wonder and which one is having a legitimate breakout. For example, look at Derek Lowe. After his 20 win, sub 3.00 ERA, sub 1.00 WHIP season last year, people were drafting him in the second and third round this year in most drafts that I was in or mock drafts I saw. He hasn't been a complete bust, but has been a back of the rotation starter at best. A few years ago, Jose Lima came out of nowhere to win 20 games and then fell totally apart the next year.
Loaiza I think is a higher risk than Schmidt by far, because Schmidt has at least worked somewhat up to this point, while Loaiza came out of nowhere. Schmidt I still think will be a top 20 pitcher next year, but just won't be a Cy Young candidate. The thing I worry about with him is his excessive workload, and past history of serious arm problems.
I'm not saying you shouldn't draft these guys or that I wouldn't draft them next year, but usually people will overvalue pitchers coming off great seasons and draft them way too high. I wouldn't draft Schmidt before the 5th round, or Loaiza before the 8th round, because the risk is so high and because there are much safer picks that are better values than taking a huge risk on a possible one year wonder.