This sounds very, very weird and "blame-y" to me, sorry. If I as a jungler see my mid laner winning, I sure as hell will focus on other lanes. If, in the meantime, my mid becomes overconfident and allows the enemy jungler to get the opponent midlaner back to the game by ganking, that IS the freaking midlaners fault. If midlaner is winning lane (my midlaner), that usually means the lane is pushed, and midlaner should roam a bit, or at least get mid tower. Both of these are relatively risky options, but it depends on their map sense, because there are three lanes to play in this game, and I cant just say "okay, even though mid is winning lane, lets babysit in his bush anyway". There are very few crucial differences (like making sure that a snowball mid at the opponent does not snowball, etc), but otherwise, if you get ganked by enemy jungler, it is NEVER the team's jungler's fault.