I disagree with Adam here because I think his standard ("Could this player be an important player on a good/championship type team?") isn't applicable to an #8 pick or to a team in the Bucks situation.
Realistically the #8 pick rarely lands even a starter on a "decent" NBA team. Since 2000:
2000: Jamal Crawfrod
2001: Diop
2002: Chris Wilcox
2003: TJ Ford
2004: Araujo
2005: Channing Frye
2006: Rudy Gay
2007: Brandan Wright
Too early to say much about Wright but looking at that list, Rudy Gay is the only one that stands out as a guy who could obviously be a important starter on a contending team. Of course any of them could be a starter on a championship team if the rest of the teams rosters was full of Paul, Kobe and Duncan type players.
Aiming too high and having unrealistic expectations which make you foreclose certain more realistic/less profitable payoffs can obviously be a mistake. To take an NBA example, think of a player who stands adamant demanding a 12 year a million contract but the best any team offers is 10. Then the market changes and 6 million ends up being the most any team can pay. Trying to get too much can cause you to end up with less than you would have got if you were more pessimistic/realistic about the possible outcome.
Just getting a complimentary type player with the 8 pick wouldn't be a disaster; looking at that above list, it would be a real steal! Even if Eric Gordon only ends up as a a Ben Gordon 6th man/occasional starter (or worse, a Barbosa), that is not bad for where we are picking. Its also something that would be a valuable trade asset in the future - lots of teams wanted Ben Gordon a few years back when he was the next Andrew Toney (incidentally, another key undersized contributer on a very good team and one that was never considered a top 10 player).
Better to end up with "just a Ben Gordon or Barbosa" than to draft a Haislip/Pryzbilla/whatever just because they have the size to theoretically be starters on a good team. That's part of why I'd strongly consider Gordon as a pick - even his floor is probably a player that has decent value at least while he is on his rookie contract.
The questions about his leadership, ball-handling, passing etc to me are more important than the size ones.