Deveryanchenko and Jacobs was both trained by Andre Rozier. Rozier trained Jacobs to beat and KO Deveryanchenko. Now Rozier is back with Deveryanchenko and training him to beat GGG.
It is weird because Rozier is a knowledgable trainer who would have knew the strengths and weaknesses of both fighters and because he was in Danny's corner, may have targeted Derevyachenko in way to expose some of his flaws to get a win. Any other trainers watching that fight might find it weird. Rozier now is working with SD again as if he was always in his corner. This is kind of weird, not as weird as Kirkland/Wolfe which is a whole nother kind of weirdness.
It was very weird because a lot of trainers that train the same guys in similar weight classes are very outspoken that they won't get involved if two of their guys are tasked with fighting each other. I recall when Manny Steward for instance was managing K-9 and training Cotto and that fight was tossed about, he said he wouldn't be in the corner for either, he'd just sit in the crowd.