Wow, that team has only once won fewer than 90 games...
[/tangent]
During one of the longest stints I had in an online league -- 10 seasons -- I took over a middling Milwaukee Brewers club and worked really hard to build them into a contender. I won several hard-fought Division Titles, a pair of Wild Cards, and never won a Playoff Series. I won between 88-98 games/year. I was
always the weakest playoff team. Atlanta...go figure...won about 120 games per year, the Western Div. champs (Colorado) about 115.
Eventually, I realized something was wrong. I was selling my soul every year to stay at about 90 wins. The other teams raped every other GM in the league, stayed young, kept winning 120 games a year.
I learned a valuable lesson...
There are great online GMs. I've been in leagues with a few of them. Their teams don't win 120 games a year.
There are opportunistic GMs whose vision extends no further than bloating their own record at the expense of community fairness and fun. The league I spoke of above was loaded with a few of those -- and other nasty sorts, which I won't detail here.
Then...there are less than good GMs. Lets face it, they are out there. They can be the nicest people, good guys, not totally incompetent but generally not up to snuff. I've been in leagues with guys like that, too. Beyond that, I'm one of them.

The most naive of these poor dolts are the folks who support GM #2...the opportunist.
Of these three, the opportunist (barring, of course, the cheater) is the only
bad GM in Online League play. Good GMs don't take advantage of bad GMs -- to the detriment of their peers, to the detriment of league balance, to the detriment of fun.
[/tangent]

OK...so that was pointless, and not meant as anything accusatory...but I think -- where it can be applied -- rank opportunism is not the same thing as being a 'Great GM'...and I'd think twice before joining a league where a team routinely -- we're not talking aberrations here -- finishes 45 games above the 2nd place team.
No fun....even if there is no cheating.
I'd delete this...it is pretty pointless...

But since I rambled all this way, I'll just leave it up. Take it or leave it.
EDIT: And before anyone comes and snipes away...this is meant more as generalizations and not a commentary on the above posts or the above league. If it is legit and the owners like it...that is really all that matters.