It's weird listening to a radio broadcast as if it were a TV broadcast. I've always liked the one guy is primarily responsible for x innings, and when both commentators are present there's no obligation to have a back and forth. The Brewers' setup (with one announcer being able to disappear) is unusual. It's something that Bob Uecker requested sometime back in the 1990s. I think you'd most typically find two play by play announcers in the radio booth, with the second one almost always present. The Cubs and Yankees each use a play by play and color person on radio. I don't know what the Braves do now, but they used to switch their radio and TV crews mid-game. With Don Sutton as part of that, he must have been doing color when he was on the radio end.