Her jab isn't bad, but a jab alone isn't enough to close distance to get into clinching range without some head movement. For a lot of fighters (GSP for instance), the jab was an excellent setup because they would follow by changing levels into a double leg, so their opponent's counter would go over their head. In her case she would jab, and then reach with out stretched arms trying to get koshi guruma (neck wheel), all the time her head held high as a steady, easy to hit target; Holm wasn't the first to tag her coming in, but was just the most effective. Meanwhile GSP rarely got punched on his way in, even in just his first years of MMA (fewer than Rousey has at this point) against considerably better strikers than anyone Rousey has faced.
Yes, it takes years to master footwork and head movement, but she doesn't have to be Whitaker or Mayweather level, even the basics as shown by most three year old amateurs would do the trick, since she doesn't have to stand in the pocket, she just has to move through it without getting hit hard. And unlike those amateurs, typically school kids who only have a few hours a day to practice, she's a full time fighter, and even dividing up her training into different areas has more time to spend on boxing and head movement than 95% of amateur boxers - and has had five years to do so. And yet she shows absolutely no head movement (seriously, has she ever slipped even a single punch) and very bad footwork. How is that possible? Any normal boxing coach who had even an average teenager for two hours three times a week would produce much better defensive boxing than that in a couple of years. She's had five and more hours, and is far more naturally gifted than 99% of amateur boxers.
Yes, extremely good striking is a sign of specialization which doesn't work. But she only needs adequate striking, and only defensive striking at that. Look at Frankie Edgar for instance, a wrestler with much better head movement after five years than she had. Or BJ Penn in his first five years (and he's considerably better than her on both the ground and feet). Even Matt Hughes, wrestling specialist, slipped punches getting into the clinch even when he first started. Or just about any of the UFC fighters of her generation (the men anyway); all have the basics of foot work and head movement, while having very solid ground games.
This is what her mother, who knows how quickly she's capable of learning, got so mad about. In five years you can't learn even the rudiments of defensive boxing? Again, we're not talking about being great, she just needs the level of a three year amateur boxing. And yet she looks like an absolute beginner in her footwork and head movement.