i agree with mrslam. its hard to simplify this but generally his approach sounds legit. d1 guys with 90+ per, and close to 90 per/spd/bh, those guys usually are +2.
the uh, the FAQ or whatever that is from, i would just ignore that. that sounds pretty dumb and useless. here's how i would put it:
- there does seem, in my opinion, to be a small benefit from a shot selection / efficiency standpoint, from running a -1. as in, you'll take fewer 3s, but at a little higher % than you would have otherwise. perhaps this is purely because those -1 guys are taking more 3s against heavy - defenses, or crap guards, or whatever. or maybe the -1 also provides a direct boost to 3pt% (it would be both if anything, direct and indirect) - but it is pretty clear that whether indirectly or otherwise, the -1 improves 3pt%.
- on the + side, is the opposite effect in play? probably, but its very slight. i run guys on +2 all the time, i've had a fair number of titles with my 2 best scorers on +2 scoring 18-20 ppg, and they still easily break 40% 3s on a really tough schedule. if +2 hurts your top end guys 3pt%, i would estimate its around 2%. as in like 40% at +2 vs 42% at 0. in this case, im pretty positive no direct penalty exists, but i do think you pay a similar indirect penalty on shot selection. like how against a +3 for example, a dude at 0 is taking fewer 3s, and making up for them against a -3, so he ends up basically taking more of his 3s in favorable conditions (on a % basis). the +2 dude is taking 3s no matter what, even though a guy on +2 will still adjust significantly to what the defense gives them, especially if they have a bunch of lp. so the efficiency drops on 3s, because the player is less adjusting to what the defense gives him. but if you were to say, when the guy actually goes to take a 3, a specific 3, of specific difficulty against a specific team - does the +/- of his 3pt scoring affect efficiency? i'm guessing not - both for the + and - actually. i think its all indirect effect. but on the +, i would almost say for sure - there is no penalty outside of shot selection. the - is murkier. i've seen some weird **** there and i do not lean strongly either way.
- teams should usually be roughly in the 30%s for 3pt attempts, as a % of fga, (1000 fga -> 300 to 400 3pta, higher end for lower division teams, perhaps middle-ish for d1 teams). obviously some fluctuation in there, you can be down around the mid 20s and still be really good, you can see freak teams up around 50% who are still pretty good. mfnmeyers can run with 0% and be pretty good, although i doubt that's the optimal way to play fb/fcp. but anyway, its just WAY easier to get your 3pt% up in that range, at an extremely efficient rate, if you use +1 and +2 heavily on your best guys. therefore, i would definitely recommend doing so.
i will qualify all of this, i tend to only really pay attention to really good 3pt scorers (my whole scheme relies on the foundation of elite 3pt scoring from a few elite 3pt scorers, that is the one constant i use across all schemes) - i suspect the shot selection benefits/penalties for the +/-, those have got to be bigger when you are less consistently excellent. a dude with 70 spd/per/bh is going to pay a lot more for forcing the 3 than a 95 per 90spd/bh guy. and he'll probably benefit on a % basis, a lot more from a -1, than the 95 per guy. so be a little cautious in taking what im saying here TOO far, especially if you are not really competing for titles regularly yet. don't get me wrong - the +2 should be part of the playbook of basically every coach out there. its just doesn't feel so mandatory until you get into the higher end players. mandatory is probably the wrong word. but strongly indicated, perhaps?