And coh2chart.com says exactly the opposite.
The only reason why axis is winning more in teamgames is because you have to micro more as allies in late game, which most players can't handle in higher teamgames. There is a max micro for both sides, but it's higher for allies in teamgames. What's more is the snowball effect that allies have when losing tanks/squads in teamgames which is really hard to recover from.
When you reach a high amount of micro and oversight of the field you'll notice OKW isn't really all that special. Ost is probadly harder to fight against then OKW in high teamgames. Nerfing suppresion was a huge nerf to there early game, they lack supression, it's so easy to push OKW off.
This does not count in 1s and 2s of course were both sides argueably micro the same amount.