I think the point
twslam07 is trying to make is not that any of this guys can contribute to the 2nd unit... a 3rd PG (or lead ball-handler) is more like insurance, you don't need it... until you do and then you wish you had it.
As mentioned before this is much more crucial when it comes to the PG spot since all other positions can be more easily filled, Casspi and Gay are bad options in that regard, they are good playmakers for their position- as the good assist rate for their position indicates- but they are far from good enough as lead ball handlers, there is a difference between the two.
Collison played 45 games last year and Rondo hasn't played over 68 games the last 5 seasons- is there a chance they won't miss games and this all conversation is redundant? sure there is, the question is should you take that chance.
By the estimation of most people on this site (as opposed to the national media and Vegas) we are a border-line playoff team- and that is key here.
Contenders can take chances because their place in the playoffs is near guaranteed and even if they bet wrong they have all the time they need to fix it.
Lottery teams can take chances because they have nothing to lose.
But teams fighting for the playoffs in the west have a small margin for error, and so even if one of your guys get hurt and you can get a new guy within 5 games- that might be the difference between making it and not.
At the end of the day this all discussion is about a small issue, but this issue can turn out to be important down the road. the question here is about risk/reward- and I think that this is an unnecessary risk taken in return for an extremely low reward...
even if Dukan proves to be as good as a shooter as he was on summer league (and not the way he was in college) he will still remain behind a ton of SF/PF we have in the rotation- we just signed Acy that should be almost out of the rotation himself.
And Curry for that matter sees 5 guards ahead of him... he (like most 3rd PG's suggested) probably wouldn't play as long as players are healthy, but unlike 3rd PG's suggested- as a player who's natural position is SG, doesnn't hold NBA experience and haven't proven his abilities can translate to the NBA- he doesn't give you the "insurance" those other players gives you.