Firstly, if you think what we've seen from Labour over the last 18 months or so has been effective, well, that's your opinion (man). Personally I think Labour is a shambles right now at the strategic, organisational & operational level. But either way, don't be this guy.
It is possible to have an informed view & think Corbyn has been failing.
It hasn't been effective at all. The in-fighting in Labour though is predominantly caused by factions within the party who want a different leader who will pander more to a right wing media. They don't feel Labour can win without it and believe it's the best option even if it means compromising on principles. Corbyn can't be bought like a Tony Blair and he sticks to his guns (misguided or otherwise) despite whatever gets flung at him.
In terms of actual policy, it's not like those factions within Labour are so very different as we saw when Owen Smith went up against Corbyn in the leadership election and didn't really have anything different to offer. I'm no big Corbyn fan and he wouldn't be my personal choice as leader... but a lot of the narrative about his failings are less to do with real failings on his part and more to do with a right wing media that will do whatever it can to ensure he can't succeed.