You cannot have it both ways, either Shane is awesome, one of/if not the best and the races and format in these tournaments does not allow his superior skill to prevail, or the races are enough to allow the cream to rise to the top and Shane is simply not the cream of the crop in these events.
Pick one.
Nope, not that simple.
'Best' doesn't mean shane beats every other player 100% of the time.
'Best' means shane beats them more than 50% of the time.
You can look at individual games, or short sets, or long sets.
But no matter how you package the race, there is always a chance the weaker player can win.
It might surprise you how big that chance is, and how little the race length affects it.
Let's say Shane has a 2% edge on Alex in 10b (they're tied 1-1 in TAR races to 100).
If they played a bunch of races to 11, shane would win 57% of them. Alex would still win 43% of them.
"OK so that race is too short. But if we lengthen the race then the better player should definitely win".
Surprisingly, if you lengthen the race all the way to 100, Shane's odds jump to 71%.
But alex still gets there 29% of the time.
So, even lengthening the set to 100 isn't enough to DEFINITIVELY answer who is best,
and no multi-player tournament can do race to 100 realistically anyway.
So in that sense you're right: alternate break easy-9-ball-break doesn't absolutely prove who's best.
Neither does race to 100 with no magic rack and 10 ball.
Neither does a 10 foot table, 4 inch pockets, and so on.
Tournaments cannot definitively prove who is best, unless you want to do race to 1000 or something
and have it last a full year. All they can prove is who's playing best THAT DAY.
And to fairly prove that, both players must get chances.
Each player getting 10 breaks, and a fairly predictable ball on the break, fits the bill.