I find in lower level stuff healer tends to get the auto-coms (if no body really stood out). For tank it's a little hit-and-miss in any content, I've got a lot of tank friends, and most the time good main tank gets ignored in favor of barely-competent healer lol (I would know, I've been that healer).

I've noticed with the way the newer content goes, people are paying more attention to DDs for coms. They can see when things are dying so fast healer doesn't even really need to heal, and with all the recent DPS check content, and the desire to speedrun for tomes/relic, it has made people appreciate the DDs that can at least adequately perform lol.

But overall I find coms don't get sorted based on performance. Most of mine have come from simply being friendly, or because I'm the lucky DPS with the raise button when healer goes down. I'm sure someone out there has given me one or two for doing good at my Job, but most people don't really pay enough attention to tell the difference.