Rashad and Charlie had chances to win without Taliek. Instead, they lost to a 10 seed and an 11 seed (with no Charlie) with a supposedly more talented point guard. They also won one BET game in 2005 and none in 2006. They had a chance, but McNamara was allowed to step right into the tying three. Taliek greets him at midcourt and makes that shot a helluva lot tougher.
In 2004, UConn pimp-smacked UTSA, DePaul, Vandy and Alabama on their way to the Final Four. In 2006, we were down 12 in the second half to Albany.
Truthfully, the best argument against Taliek is Ben - who was able to cover for some of Taliek's weaknesses (primarily late game/late shot clock creativity and FT shooting). I don't think Taliek would have been nearly as successful without Ben. But I also think they covered for each other - Ben played with zero emotion and didn't really like to dig in defensively or dive after loose balls. He wasn't an emotional leader, and didn't have to be. Ricky and Khalid covered for each other's weaknesses in the same way. And frankly, neither Ricky nor Khalid proved to be very successful without the other (compared to their success together).
I do imagine, for example, that KO could have filled exactly the same role in 2004 that Taliek did. We'll never know, though. Hypotheticals are nice with their undisprovability.