Yahoo draft grades are garbage, to be honest. I always get Cs. That's because I refuse to take more than 1qb and 1te. It always gets me for lack of depth. Why would I grab an extra QB when every other person in my league has 2? By not grabbing an extra QB, I essentially free up a roster spot while having access to any number of favorable QBs based on matchups..
We do an auction waiver in my (favorite) league. You get $100 at the beginning of the season, you can bid on a guy if you want him on your roster. In a normal league where there's no reason not to grab a waiver, there really isn't a lot of strategy.. just take a look at your prospect compared to your bench - do you think that waiver pickup has more upside?
As stated above, I hate wasting bench positions on QBs and TEs. You're going to start your QB for like 12 weeks out of the year, so why eat up a bench spot with an extra QB? Same with TE in most cases. I'd much rather have a WR or RB on my bench that has a lot of upside and could be played at a flex spot with minimal risk if he looks like he's catching fire.