I would agree with the synergy point. Outcasts as a faction have little. Gremlins and Hamelin have quite a bit within their own crews, but Viks have little real synergy, the mercs can be custom made to each situation, but have little real synergy between specific models besides the Korps. Levi only has real synergy with his creations and things he can give crows to like the Ss miner and Noir.
Their strength, in tournaments, lies with the fact that your opponent never knows what's coming, because each master/crew operates completely different and need specific things to counter them. We also have one of the top 5 in Hamelin, so I wouldn't say that we come out that bad in the end.
Levi was a top master in book 1, but the rise of super fast crews (dreamer, kirai, collodi, etc) sent him down into the middle ground. Hell, any guild.crew with 2 austringers will give him a lot of trouble. So barring those 6 crews, levi stacks up quite well against the other 60% or so of crews. Now, ill admit that I haven't used him with collodi yet to see how that works out, but I'm still a bit sceptical that it will make him THAT good.