I have watched Webb run since 9th grade. He won a conference championship as a freshman in the two mile with a kick only the best 12th graders could have accomplished. He is the best American talent I have ever seen, and heck, I am old enough to have watched Ryun run back in the 60's.
I am reminded of Alberto Salazar, a runner who did not have Webb's talent (although far more talented than he lets on). In reading his book, it is easy to forget that Salazar's great period encompassed five years, and yet, for ten years thereafter, he kept at it, always chasing the hope it would come back. Salazar spent far more time in frustration than in glory. I also think of Chris Lukezic, Webb's training partner, who knew in my view when to call it quits. And of course, Herb Elliott....whose flame burned so brightly and intensely he intuited he should quit.
I do think people age differently when it comes to running, and a decline in a speed event at age 25 does not surprise me. I recall being worried when watching Webb's 1:43 800 against Gary Reed, as I was persuaded he hurt his hamstring in the last 40 meters (I believe he did), and was concerned how he would recover.
I wish him well, and hope he and his new family prosper.