this strategy is a good one, but it only works if both players are good at circling in those two areas, it's not a good strat if only one player is good at it and the other one is constantly going down. Honestly, there are quite a few ways to get to high rounds on this map, this one, is by far the quickest way to get to get there but it involves a bit of coordination and experience for two players kiting on this map.
The mpl area/minecart is a tight and narrow area for someone to circle around and almost always a napalm zombie will spawn in the upper left corner opposite of the mpl. I have tried working with others with this strategy and almost everyone has a problem holding and kiting the minecart/mpl area and i've been forced to clear the round myself. Dont get me wrong, it's a wonderful strat that clears rounds fast and efficiently, but it's not a strat i'd suggest for people who have problems kiting and hording zombies in tight/enclosed areas.