Should I capture this bird and take him to a rehabber?

Found a robin flopping around on the ground walking my dog in the woods this morning. I called Molly away before she got to him, but he still seems possibly injured to me. I think he may be a fledgling – it’s the right time of year, he’s smallish and has short wings, and the feathers on his butt are downy. He does not appear able to walk, but flops forward like adult injured birds I’ve seen. He should be able to walk, right? It is raining right now, and I know that can affect young birds who don’t oil their feathers yet, but even if his feathers are too wet for him to do the fledgling fly-hopping thing, shouldn’t he be able to walk and to fold his wings properly against his body? I watched him for about 15 minutes and didn’t touch him.

I can probably go find him again and usher him into a box safely if you guys think he’s injured. Quick answers much appreciated.