I'm not saying the gap has to be as big as a Yonko and his commanders but rather that it has to be noticeable gap.
If it turns out that Akainu is awakened and the others aren't then that scenario would meet the above criteria.
Just to be clear you don't think that the Admirals would be fighting the SHs in any significant capacity at any point in the series?
If not then, you think Luffy would fight Akainu and then non-SHs would be pit against the other Admirals?
1.Akainu vs Luffy is never concluded
2.Akainu falls before the Admirals
3.Akainu gets some powerup (from Imu?) and fights Luffy
4.Zoro and Sanji are not defeating Admirals.
5.Zoro and Sanji defeat Admirals with help (weakened if solo fights) while Luffy solos Akainu without help.
These are the only options for the Admiral fights. That's just how Oda writes. Under no condition is Sanji going to be defeating an Admiral solo before Luffy, that is what will happen if they all fight at the same time (thus it's not happening).