It's a testament to the quality of the writers and the collective vision of what the show was about.

@CrazyIvanova said:

This is one of the few shows I can think of where swapping out characters actually seemed to work. On most shows when they switch a main character for a new character it just doesn't "fit" right. In this show, on the other hand, it usually worked out better than before. I liked BJ better than Trapper (although I actually liked Trapper better than Hawkeye), Potter better than Blake and Charles better than Frank.

The Law & Order franchise did pretty well with new characters, too.

It was truly sad that Henry didn't make it home. And when he, Trapper & Frank left, you missed them but the replacements added to the show.

But nothing/no one replaced Radar , not even more Klinger.

@WalkGood Funny thing about Radar was that he seemed to "de-evolve" as the show went on. Yes he was always the naive Iowa farm boy but, in the early seasons, he wasn't always so squeaky clean. He smoked cigars and often drank something other than Grape Nehi. It was the later seasons that he became more a caricature of himself. You're right, though, Klinger wasn't as good a replacement. Can't hit every time I guess.

@CrazyIvanova said:

Grape Nehi.

I had to Google that. I was under the (mistaken) impression that the drink was called Grape Knee High, as in knee high to a grasshopper. I thought it might have been slang for Coke, and a reference to Radar's childish naive nature.

You live and learn, huh?

Yes live and learn, "die and forget it all" as my mother says (but she's a very depressing person)

Those in charge were smart enough not to replace the departing characters with essentially the same one. Therefore, Potter was regular Army to Blake's loose command, B.J. was a strong family man to Trapper's mostly impish immoral character, Winchester was a brilliant upper crust Bostonian to Frank's inept low brow character. I think CBS' MASH was slow to launch because the TV cast had to (necessarily) closely replicate the movie cast, which is difficult once the character's are known.

No one replaced Radar as it were. Klinger was already in the cast and while he moved into the company clerk position, he was still mostly the same Klinger (minus the feminine attire).