"The disparity of injury is evidence of an ambush style attack"
Fair enough, but it's speculative / circumstantial at best. I personally believe that TM punched GZ in the face and that he was on top of him in John's backyard. I just don't think GZ is a credible person, so I look for evidence of how the fight started, and find his story wanting.
One can also speculate and build a circumstantial case that GZ left the innocent path to(wards) his vehicle in an effort to detain the teen. One story is as good as another, except that Trayvon Martin didn't live to tell his side, and GZ's version of other events is fraught with contradictions and inconsistencies thus throwing suspicion on anything he says, to say nothing of his behavior in regards to his hidden money and hidden passport.
The Sanford PD never found anything other than GZ's statements to say that this TM was the aggressor up by the T while GZ reached for his cell phone, etc. In fact, they found seemingly contradictory or inconsistent statements such as he fell backwards to the ground vs. he stumbled forward past TM's position for around 50 feet or so and never seems to have grappled with the teen at all yet somehow they all drop several objects about. In every telling save one, GZ seems to claim he was sucker punched to the ground where he stood more or less. The distance from the T to John's back yard will be established by the total station map we are liley to see monday, but IMO it's around 50 feet and that's a fair distance to leave out of a story given all that could happen as the two may have traveled it. GZ gives an account during the walk thru but not until that time does he ever mention any such travel by the two of them.
If you say a jury might buy that the disparity of injuries is evidence of an ambush, I'll concede the point, but SPD never seems to have found any witnesses that it happened that way, and plenty of material that suggested that GZ is not a credible person. They also didn't seem to think his injuries matched his story.