Yes it definatly changes. I had a shooting guard who became a point guard all of a sudden. And he didn't even got a pop. I was training passing at that time.
Therefor I think the 'best position' is constantly calculated along with the training update, and it takes the real figures, not just the levels we see, in that calculation...
So far 'best position' realy doesn't matter to me. In fact I have no power forwards, and I play some of my centers or a short forward as power forward. I also had my best PG play as SG in a few games, and recently I even have centers playing as SF since my 2 SF are injured. I can't see any negative effect about it.
I think the best position thing is just a little piece of info for starters, so they have a clue how to put together their first line-up. After a while when you know better what you're doing, you might notice that the PF you never play since you have 2 better PFs is actually better than your SF, and play him there.
1 last thing. In the all star game I had a shooting guard elected to play on the SF position, and a SF elected to play as PF. The last one even took a prety big part in pulling the win to our side as well!
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