You wanna know about how good an idea it is to have, say, Marc Bulger and Torry Holt starting each week. Holt catches a pass, double points. He catches a td, instant 12 (throw S. Jackson in there, and you'd be unbeatable). Not a bad idea, and it has worked for me before. I wouldn't design an entire draft around it. If it falls in your lap, go for it. Just keep in ming that if the Rams, or the Colts, or the Bengals, or whomever you've based this on get shutout, then it's a good bet you've lost your matchup that week. You never want to hand a week away (especially if you are playing for $$).
As far as coming out of three rounds with 1 RB: If he's a workhorse and you have a top QB/top WR or two great WR's to go with him, it is not as bad as it looks (especially in ppr leagues). It's a RBBC NFL nowadays, and few RB's make it a whole season. There'll be other, solid RB's in rounds 4 and 5 anyway.