Obviously it's nothing major, and he's not fat. He's in good shape by non-athlete standards. Maybe 'too much' is harsh. He can obviously play well enough in his current shape. But he could benefit from a tiny bit of trimming down.
I expect any Premier League footballer's abs to be visible. But I think he could do with losing a little bit. Heck, I'm sure even he'd agree that he could get himself into slightly better shape.
Like I said, I think he's a natural muscular guy. One of those who always looks like they work out, and carries their weight well even when they've let themselves go a bit, but needs to work more on keeping their body fat down.
For example, Rooney's no less trimmer than Shaw right now, and I doubt his abs will show like that.
Obviously stamina doesn't 100% correlate with how overweight someone is. You either have it or you don't. But he'd just be that bit quicker across the ground and on the turn.
Hmmmm.... I'm probably just over-analysing things.