I always remember Karpin when I think of Mostovoi. Russia basically had a better team back then. That USA '94 team with the two and Beschastnykh plus Onopko, Salenko, Popov, it was a good side in a very difficult group.
This may sound funny, but a huge reason why we had a better national team back then is that Russian clubs were poor then but are rich now. In the 1990s, Russian players had to go abroad to make reasonable money, and in order to be successful abroad they had to work really hard. Today Russian clubs are very rich, Russian players have huge salaries (in part because we have a quota on the number of foreign players on the field), and they have no incentive whatsoever to move abroad.
In the 1990s, Mostovoi, Karpin, Alenichev, Nikiforov, Onopko, Cherchesov, and many, many others played abroad; today, only Cheryshev plays abroad at Villarreal. And because Russian league is far from great, players don't compete against good opposition on a regular basis and don't make any progress.