For years, I did a lot of training, strava watching, and group rides, but no racing. You can really delude yourself into thinking you are fast simply because you can hang with a fast group, beat your riding buddies regularly, or your watts look good on a trainer session. When you jump into a race, usually a lot of those recreational riders are gone, and you are in the company of folks who are pretty darn serious about going fast on a bike, and train just as much or more than you. Those same guys that let you take a hill on a fast training ride, bring the pain unmercifully in a race.
My first racing season, cross, in a long while has been very humbling. When I was younger, I didn't have to balance work, spouse, kids, and other activities; training and racing seemed effortless fun. It's much different when you are the one trying to stick with some group and hang on for dear life. I've learned a lot and realize that I've got to change the way I train, if I am going to be even reasonably competitive with the folks who are regularly racing.