Not exactly. I read that Burgoff, in an interview said that the taming of Radar’s character was his idea. He didn’t like the way Radar was portrayed, so sometime during the show, he asked if he could change Radar into a naive, innocent, Iowa farm boy.
So this was an intentional, and unfortunate, conscious choice by Burgoff. I personally never understood the logic, but at the time, MAS*H was a very popular show and Radar was a very popular character. So he had some clout.
In the first season, Radar drinks alcohol and ships a jeep home in a box. Later seasons show a commitment to Grape Nehi and rabbits and other animals. It was a really odd shift in who Radar was, and changed his character into one that many people didn’t like. He was basically the dame from the movie and seasons 1 and 2, but somewhere along the line they really re-wrote the entire character.