Well, first you supported Joe until the day he retired, now you aren't sure if Carville is correct saying, you can't play your seventh string qback and expect to win the big game.

Well, neither of those statements is true - but also, neither of them have anything to do with whether Harris would be favored to win the nomination. My comments about Biden were that the Democrats didn't have the ability to force him not to run, and that even if they did it would be unlikely to yield a better result in the Presidential election. That was true, up until the disastrous debate performance - which changed those calculations. Even then, switching to another candidate didn't help them much; as expected, it ended up being Harris, and as expected she didn't have a successful enough campaign to win.

As for Carville's quote, in 2023 Harris wouldn't be the "seventh string quarterback" in a primary. She was the incumbent vice president (who nearly always win primary contests), well positioned demographically to appeal to the Democratic electorate, has massive fundraising resources compared to most of the rest of the field, and advantaged by the calendar front-loading South Carolina and California. She's the star quarterback in that race.