Very funny how quickly the fantasy community writes players off. If Oliver has a great 1st half, come the break, these naysayers will all be hiding, or claiming they 'called it'. I'm torn on him myself, but I feel there's an equal likelihood that he could return to the form we've seen as seeing him bomb again. With the word 'upside' that's thrown around so much, it's a joke to see Perez looked over, if upside is what you're looking for.
Now, I haven't taken the time to read through the thread fully, but I think Joe Blanton is a big candidate to break out and shock some people.
As for overlooked, Doug Davis continues to fly under the radar it seems, as does John Lackey, whose numbers speak for themselves. Dontrelle Willis appears to be far too undervalued from what i've seen this year as well; even if he's one of the 9 best hitters in Florida.
Bonus: I said it last year, was ripped for it, and then the naysayers disappeared, never to be heard from again. I'll say it again. Draft Brian Fuentes. You'll be happy you did. You'll get him late, you'll get real nice stats from him, and he'll help you win. Expect 30+ saves, 100+ K's, a sub-3.00 ERA, and a WHIP hovering around 1.20. Now compare that to where guys like BJ Ryan and Chad Cordero are being drafted, with owners citing the 30+ saves and 100+ K's as their reasons for taking them where they do. Again, draft Fuentes. You'll be glad you did.