For DK NFL there's an option to force the FLEX position to be WR, TE, or RB. I wouldn't mind a similar option for NBA. Or maybe just some restrictions by position (similar to the way team restrictions are set up).

For example, last night I only liked 3 SFs. I wanted all my lineups to have exactly 1 SF in the SF slot and none in the F or FLEX slots. In order to get it to work the way I wanted, I had to only have 1 SF in my pool and do various runs. Otherwise my lineups might have 1, 2, or 3 SFs.

(Alternatively, I guess I could have just given them super low projections.... )