its sorta not the question but players who were at the top would be able to come back and have the ability to get there again if they really wanted too. Bringing the old meta directly to compare would be hard, just get all the old invite players in their own league where they dont have to adapt to the new meta and can play the old game until they arent rusty, then put them up against current teams and then we would actually be able to see but thats never going to happen.
I guess the closest thing we have seen to this was when AU meta met eu and na and vise versa. So to try and go back to the question is that old players wouldn't be as mechanically as sound as they used to be and would naturally adapt to the meta instead of having the raw skill to be able to play with the old meta. I would assume that the "old meta" wouldnt work anymore because otherwise top players who have been playing throughout all the changes would be playing the same way now.
I dont even know if any of this makes sense, probably just went off topic.