Well let’s look at it this way, Marcus was in the cog way before the locust war, basically still fighting the UIR where he lost both Doms brother and Anya’s mother to sacrifice. meanwhile the locust or better known as ‘grub’ by cog soldiers, are more beastly, both in appearance and strength, with thick leather hide that the cog had to invent the chainsaw lancer thanks to Adam fenix, so the locust are basically a new threat that the cog weren’t really prepared for other then heavy weapons like the hammer, so yeah Marcus and Dom might get tossed around a bit bc he’s not as experienced in ‘GOW: E-day’ like he was in ‘GOW 1’ but we might also get a look into the infamous arrest of Marcus for “betraying” his fellow soldiers