drop bear
Sr. Grandmaster
True of all grappling arts. That's why strikes are needed. If you have a low entry (single/double-leg), you might be able to slip in below the big guns, but you're still working to penetrate his specialized range.
The reason they do it is to sort of guess the other guy will strike at the head. So that they can be moving in to the grapple while he is going for the strike
That way it is one beat vs one beat and they have a bit of initiative.
Do make all of this happen you have to understand how boxers work.Otherwise you are going to try to parry the strike and enter on that same level and more likely than not get your head punched in.
Once the distance is closed. Then boxers have to understand how grapplers work.
Effective strikes are needed. Not Rhonda Rousey boxing. If you are getting smashed apart by the better striker. Desperately closing the gap is still a risky proposition.Because you generally hit that close from too far away.