Do you have a list of what 4 bots those were? I'm wondering because robocode-archive.strangeautomata.com doesn't automatically update when the same version number already exists.
eem.EvBot v4.4.5, xander.cat.XanderCat 12.7, zezinho.QuerMePegarKKKK 1.0, EH.nano.NightBird M. EvBot was the most recent release. My client was running quite a few battles for EvBot initially (when it only had about 400 pairings) but when it got up to the 900's, suddenly it was just running random pairings of all bots despite the 4 being short roughtly 150 pairings each. It appears as though all 4 of those bots are now getting priority again, as they have each picked up at least 50 pairings since this morning.