Ok, I think I have made it though 3 years now as Mithridites facing Sulla. Outside of the first year, I have not been pressed hard. In fact, I finally counterattacked and have captured almost all of Greece and could easily invade Italy...but I won't. Unless something unusual occurs over the next couple years, I will win with a huge VP total. My conclusion is that Sulla can't win without a navy. Control of the seas gives Mithridites too many options for counterattack and prevents Sulla from entering Asia Minor. And once civil war breaks out, Sulla is fighting on two fronts.
This is a very interesting scenario. Sulla and his veterans clearly are the dominant military force. Yet he can't win without holding territory and his veterans are not enough to do the job.
In terms of advantage, it seems Mithridites is the easiest side. While Sulla and Marius only receive small VPs for Greek stategic locations, Mithridites receives huge VPs for the same locations if he can hold or recapture Greece. And Mithridites can retake Greece unless Sulla decides to ignore Italy. In which case, he may lose to Marius. I just don't see how Mithridites can be defeated unless Sulla and Marius cooperate in defeating Mithridites first before the civil war. Yet Marius has very little incentive to cooperate with Sulla because as soon as Mithridites is defeated, then the militarily superior Sulla takes out Marius. Marius does not want Mithridites to win but if Mithridites is destroyed, then Sulla can concentrate on Marius. Both Marius and Sulla really have some no win tough dicisions to make unlike Mithridites.
This is must be a really insane scenario to play PBEM. Probably a lot of fun. I think I will see if there is any AAR's out on the scenario.