>>149553255You could probably get them into game shape if you got them working on their cardio far enough in advance, but the other issue is that despite the seeming similarity because it's fat dudes slamming into each other the sumo skillset doesn't really translate to football. The goal in pass protection isn't to get a guy off his feet or ring him out so much as to just not let him by you. You can't grab and hold (insert Chiefs joke), you can't hip throw people, you can't jab people in the throat or put hands in their face. Most sumo-style moves would be a penalty so all their training and experience is wasted and they have to unlearn all their tendencies.
That being said, I imagine a sumo could still make a fairly decent o-line prospect just due to size and strength, but the problem is you can't make the NFL by being fairly decent. All those guys are like the best of the best so some guy who's still figuring out how to even play football at all isn't going to be elite even if he is a physical freak. They could probably make serviceable college linemen at lower-tier programs but what Sumo's going to leave Japan to try and learn football at Sacramento State or wherever?