The premise is simple: I'll tell you what players you can confidently start the season with, and what players should cause your stomach to wobble if you have to start them.
Kansas City Chiefs
2006 stats at NFL.com and pro-football-reference.com
Larry Johnson (RB): If you've got the third pick in your draft, and Ladanian Tomlinson and Steven Jackson have already been selected, you might think you have no choice but to take Johnson. But the pick was not foreordained by God before you were born; you were created with free will and you can make the choice whether you want to take Larry Johnson or not.
And you should not.
Larry Johnson had an NFL record 416 carries last season. Here is what Football Outsiders has found about running backs that have over 370 rushing attempts in one season: "A running back with 370 or more carries during the regular season will usually suffer either a major injury or loss of effectiveness the following year, unless he is named Eric Dickerson."
So there is a notable exception: Eric Dickerson was the freak that had several successful seasons with a grueling number of carries. So it's possible another freakish athlete will be able to withstand such overwork. Do you want to take your chances that Larry Johnson is that guy? I certainly don't. I've heard people say they aren't worried about the carries affecting LJ because he's so young, but the Football Outsiders data suggests age has little to do with this.
There are many solid options at #3. I'm not going to tell you who they are because I'm paranoid and I don't want people in my league to know who I really like. But if you look, you can find that Larry Johnson need not be a default top-3 pick.
So yes, if he's on your roster, you can be happy to start him week one. But I'd try to trade him before week one, and if he's on my team by the end of week one, I would again constantly try to trade him.
Tony Gonzalez (TE): Gonzalez is widely considered to be the #2 TE in fantasy football; just how inferior is he to Antonio Gates? Let's look at their last three seasons
The numbers suggest Gonzalez is comparable to Gates in receptions and yards, but that Gates is far superior to Gonzalez in TDs (32 in 3 years versus 14 in 3 years). Gonzalez is actually closer to the rest of the pack of TEs (like Todd Heap or even Chris Cooley) than he is near Gates. And given that Gates is younger, has a much better all-around offense to work in, and has a much better quarterback to work with, the difference between Gates and Gonzalez is just going to keep increasing. Antonio Gates should easily be the first (or most expensive) TE selected. After that, you should either wait a long time or spend a very little amount of money for a TE. Gonzalez is still a very good football player, and in fantasy football he still has greater name recognition than other TEs, but there's little separation between Gonzalez and the other competent fantasy TEs in the league.
UPDATE: You know Priest Holmes, one of the greatest fantasy football performers of all-time, is worth a cheap pick.