“How do you know that there were 3X the number of Ukrainian troops at Kiev? “
I have no idea if that number is correct, but I can believe it. Even so I don’t think it makes much difference. I believe the troupes near Kiev were its local defense forces and were less well armed. I’m not sure they are the kinds of troupes needed in the Donbas but they would probably have been useful in Kherson. On the other hand the troupes and equipment and respect Russia lost in its northern campaign would obviously have been better spent concentrated further south and east.
It makes a difference to the argument the Russian troll farm is making, which should be pinned down eventually.
About a month ago the Ukrainian army began to get reinforcement brigades of militia organized, above a local level, that it could redeploy east. Many parts of the front are now held by these militia brigades.
But back in the February-March emergency these units were not available and militia could only be used locally. They generally served very well, but they were not deployable. The only reserves the Ukrainians could redeploy were the prewar active brigades.
It takes time to mobilize armies.