As @Stefan alluded to, your best bet is to utilize the multilevel structural equation modeling paradigm. Software for this can be found both in existing general purpose programs/packages (lavaan
and xxM
in R, gsem
in Stata) and standalone programs such as Mplus. See also these CV threads.
The challenge you have is that multilevel or mixed effects models require the outcome to be measured at the lowest level of the hierarchy (players within teams). But your outcome only resides at the team level. There is no equivalent of a player win.
In multilevel structural equation models, the outcome can exist at any level of the hierarchy. However, you are still limited in which predictors can be used to explain variance in that outcome. So in your case, the player level variables can only influence team wins via their aggregate characteristics. E.g., teams with higher percentages of X types of players tend to win more often. Note that to address your second point, you can introduce team-level measures of variability of player characteristics as predictors, in addition to means. If teams were organized into leagues, then league level variables could influence variance in wins at the league level.
In principle, it is not out of the question that individual player characteristics could influence team outcomes. However, there is no software implementation that I am aware of that can estimate such a model.