Dorothy Collins was a recording artist. She was given "Losing My Mind" because of her torchy voice and trained technique. Originally, Alexis Smith was to sing it with Dorothy as a duet, then Alexis was to have it as a solo, but Alexis knew Dorothy would sing it much better and asked for a leggy dance number, so Sally has the most famous number from the show.
All this is to say, Dorothy was from the time period where theatre actors wanted to sing the music as written. The exception is for big stars who came to theatre later or actors who made a career off of their distinct "speak singing", such as Rex Harrison in the former category and Robert Preston in the latter. Today, it is much more in vogue for actors - even ones with gorgeous voices - to "act" by speaking a line here, back phrasing, or the dreaded "yell a word for emphasis". Dorothy was a singer, and she could act the entire score while hitting every note and matching the rhythms Sondheim wrote.
This brings me back to a conversation we had during the last revival of Follies - the actual purpose of the Follies sequence. It is my belief, and the belief of many others, that Sally is not Sally from the Sondheim musical Follies when she sings "Losing My Mind", but instead a torch singer in a metaphysical Follies. With that information, Sally should not be yelling and weeping as she sings the song. She should carry that torch through this plaintive Gershwin-esque ballad expressing her desire and pain. Dorothy lets you feel the emotion she is carrying with the way she caresses each phrase. Bernadette was odd, because some nights she would sing the song straightforward, but other times she would have a breakdown during the number (you can see one of these on youtube where she grabs her neck and shakes her head). Bernadette also loved to cry - or, to be honest, tear up, during the number, which a lot of people (myself included) weren't a fan of. Obviously, if you are a touch singer, you are not going to cry during your song. And you cannot actually sing when you cry, so it's an acting choice, not genuine emotion.
Imelda, like Bernadette on her worse nights, has carried the character of Sally to her Follies number, and, to me, that is a fatal error. Of course, I don't believe her voice is strong enough to make a case for the straightforward stand and deliver approach the song calls for (and she obviously doesn't have the top notes), so maybe this is a distraction technique. Whatever the reason, it's misguided and ineffective.
"Sticks and stones, sister. Here, have a Valium." - Patti LuPone, a Memoir
