Of the three guys mentioned, only Sellers was an immediate out-of-the-gate sensation as a freshman.
Quincy Douby didn't come in as a tried and true program changer. He was a high-ceiling pure shooter who had only started playing basketball during high school, and the 6th man through most of his freshman season before earning a starting spot later in the year. He averaged 12.5 points as a freshman and 15.1 pts as a sophomore, which then ballooned to 25.4 as a junior phenom.
James Bailey also wasn't a program-changer in his freshman year, averaging just 8.5 points as the 6th highest scorer on the team and shooting .588 from the FT line. As a sophomore that went up to 16.7 and he became a double-double machine, and then as a junior it ballooned to 23.5.
As far as Alvarado, he's averaging 12.5 ppg and shooting .286 from the arc this season. I'm not so sure he'd be getting much different press attention than Baker is at this point.
Don't expect Mulcahy to somehow come in as an elite program changer, either. He's not a one-and-done guy who should be headed straight to the NBA instead of college, but a 3-4 year player who will develop over time.