Lavell's last 10 years can be compared to Bronco's 10 years relatively easily. I don't think it's fair to compare the 77-84 BYU teams to Bronco's BYU because college football has changed so dramatically since then. The WAC teams started catching up to BYU in the late 1980s, so that by the time McBride arrived at Utah and Lubick at CSU, the money and stage was set so that these teams could compete with BYU. The best comparison for BYU coaches are the teams after 1991. So let's look:

Lavell 1991-2000

overall - 82-42-2 - .651
against current p-5 (including Utah and TCU) - 17-24-1 - .404
bowl record - 2-4-1 - .285
bowl record against current p-5 - 2-2-1 - .400
record against Utah - 5-5 - .500

Lavell had exactly one season with one or fewer losses to P-5 schools during this stretch - 1996. That, despite the fact that he the majority of the games were played against WAC foes.

Bronco 2005-2014

overall - 86-37 - .699
against current p-5 - 19-27 - .413
bowl record - 6-3 - .667
bowl record against current p-5 - 3-3 - .500
record against Utah - 3-6 - .333

In all categories but 1, Bronco outpaces Lavell (though not by much), and that may be the one that matters most to fans - beating Utah.

Personally, I'd love for you to keep Bronco because he's such a complete dork as a human - but as a football coach - I hope you get rid of him because your program will never recover.