Subbing corners in at safety

At this point in the game, all corners have 90 man and zone but a lot of FS/SS miss the 90 man threshold just barely even with maxed strategy cards. Specifically talking about guys like malcolm jenkins, brian dawkins, jalen mills that get eagles chem so they're 97/98 speed, which is faster than some of the other safeties that hit 90man and zone but only have 95 speed without a theme team. So recently I've just been putting corners in at safety, because stats wise they all hit 90 man and zone and guys like rasul douglas and ty law are like 98/99 speed with the hurts card on an eagles tt, and deion/adderly are 99 speed with 20 cowboys and emmitt smith. But i notice when I do this it seems like I get weak boxed, the corners can't tackle the RB on inside runs probably because they don't have the hit power/tackling that safeties have. So basically is subbing in corners at safety even worth doing? If not, who should I have playing safety? Eagles themers that get 98/99 speed but miss the man threshold? Or just rock with 96 speed guys like john lynch who hit 90 man and zone

As an eagles theme team player myself, I use rocket at FS and Lynch at SS. In dime I have 95 Krause in behind rocket. I find that with the heavier safeties I can stop the run much better and the both play very well when in coverage.