I agree with that. That's a hell of a nice buck, but he's not regressing yet.
SkagitSteel' buck this year has the classic appearance of a buck well into regression. I think he states that deer start to regress around age 10, and felt this one was older than that. I was thinking it was more like eight when deer start to regress, but I'm not going to argue with him on that. It's just a number. I'm sure every deer is different.
Anyways, (though I have no first hand knowledge) the classic regressive rack displays massive bases and main beam which continue to gain girth even during regression. Also, they typically have very impressive knurling at the bases. Finally, the tine length is drastically reduced and often appear a bit stunted/twisted/bent, and narrow quickly from the base of the main beam out to the point of the tine. An inch or two tine length seems common in the photos I've seen in the past. For a quick review, here is skagitsteel's thread with pics:
https://hunting-washington.com/smf/index.php/topic,232678.0.htmlSo to answer the question, how do you know if he is regressive (?), in the absence of photos or old similar identifiable sheds collected from the area where the buck was harvested, it is really just a judgement call that is also based on the width and amount of white of the muzzle, overall body size, etc. If he was over 10 years old, he will likely have a massive head, large body (though that might be possibly waning as well), and shorter tines with massive bases. A less gifted buck in the antler department would be smaller in antler comparison but still have the other old buck features.
Edit: Ridgefire's Halloween Buck posted a couple days ago is one to make you scratch your head. The tines appear like that of a regressive buck, he has pretty good knurling, not massive, but pretty good. His muzzle appears white and wide from what we can see. The bases and main beams are not massive - they are pretty average. Just guessing, I'd say he was probably four years old and would likely never be a spectacular buck (though I'd love to have killed him - he's a great buck in my book). It wouldn't totally surprise me if Ridgefire posted a picture of him from two years ago showing him with longer more impressive tines and even smaller main beams and bases, indicating that he was indeed regressing. Then again, he could be a two year old that was just beginning to show his potential. Ya just never know... ( I guess you could always have a tooth aged).