I have never heard the 'poor team mate' label applied to Big Al.
I've never heard Al Jefferson to be said to be a fantastic teammate either though, or much of a leader, except by those lavish platitudes GM's and lame coaches give to players they know they're stuck with.
That doesn't mean he's a bad teammate or even an ineffectual leader. Just that I've never heard anything that convinced me he was a real leader or a great teammate (I doubt he's a 'bad' teammate, but you can be a teammate who is neither a 'great lockerroom guy' or a 'lockerroom cancer').
Also, consider that very few last place teams have great or even good chemistry. Losing takes the heart out of a team, and even the best leaders' encouragement or censure might come across as little more than screaming into the wind.
Also consider that Kevin Love was leader in highschool, a leader in college, and went to a team that had an established starter at his position, yet continued to lose. I doubt 'resented' is the right word, but I doubt Kevin Love liked that he was behind a guy who he outplayed for a long time (because I believe Al Jefferson was still recovering from injury), but did so for a last place team. When you're losing and in last place, everybody begins to think they could do better if given the chance.
I don't think it is really as much of a knock on Big Al so much as a statement of how Kevin Love feels like this T-Wolves team is finally his team, and that he likes the direction they're pointed in.