you usually need to fill:
qb, rb, rb, te, wr, wr, kicker, defense, flex wr/rb/te. or some combination thereof.
but kicker and te are kinda like catcher. kicker you almost don't even need to draft, too hard to know in advance what offense will explode, and the difference between the top and bottom is not that great. TE is definitely like catcher, there are like three of four great ones, then it is a crap shoot. wr's are kinda like OF's in that there are a lot of good ones, a fair amount of great ones.
defenses remind me a little of starting pitching. can be a good points generator, but they are hard to predict -- better to invest in offense first.
the only problem is rb's are like closers in scarcity, but also the biggest scorers on the team, so it is unbalanced and makes things more the result of good draft position and making it through the season without injuries.