Sven does suffer from not really having a set role. This isn't a problem with an item-dependent hero with amazing farm like Profit (his role is determined by what he builds) or a Swiss army knife hero like Invoker, but it is with Sven. If you play him as a carry, he's ridiculously easy to kite, even with a blink dagger, and he's outperformed by both Leoric and especially Chaos Knight in that role. If you play him as a support, he's mostly useless. And if you play him as a pusher, he still can't do anything about a Keeper of the Light hanging out 1200 range away shitting out Illuminates on cooldown or a Profit that's constantly skipping around the map pushing out the lanes Sven isn't in.
Would you put Treant Protector in the same boat? A hero that suffers from not having a set role, and is outperformed by other heroes (Tide being the biggest contender) in the roles he tries to fill?
---------- Post added 2012-09-17 at 11:21 PM ----------
The usual solution to bad teammates is to pick heroes that can basically carry a team. Earthshaker is really good if you can position yourself to punish the enemy team for stacking. My last game had us start out really behind, getting ganked constantly by Storm Spirit, QoP, and Morphling (free tower diving since they're blink heroes.) I think I spent the first 15 minutes hiding in the trees, giving my PA as much solo XP as I could.
But then they stacked up with a double creep wave to push a tower, I was able to hobble over and echo slam and we wiped their team and took a tower, and that gave our team a much needed boost of confidence. We were able to repeat it two more times (they were idiots, I guess) along with some ganks and went to an easy win.
If your team isn't nothing but instalocked hard carries, you could also play a morphling or anti-mage and basically ignore your team for 30 minutes while you free farm. Profit can also pull this off if you can push multiple lanes effectively (don't do it if they have, like, a Sand King or Keeper of the Light, though), and I've noticed pubs seem to have issues dealing with a fed Phantom Lancer, too.
I'd also recommend not soloqueuing for all pick. I've noticed that that gamemode results in pubstomps (3-4 buddies partying together and then picking heroes that compliment each other to a comical degree) and "mid or feed" idiocy a lot more.