"My criteria were separate and independent from the institution [for Hadley's return]," Mendenhall told KSL radio.
Hadley had 12 tackles and two pass breakups in his first two games, against Virginia and Texas.
The Cougars will face an undefeated opponent next Saturday. The Houston Cougars improved to 5-0 on Saturday with a 25-15 win over Memphis.
Next Saturday's game will kick off at 1:30 p.m. MT and will be televised by ABC or on an ESPN platform. Whether that will be ESPN, ESPN2 or ESPNU will be announced on Monday.
Houston didn't dominate Memphis like it dominated its last few opponents, overcoming a slow start to keep its record unblemished.
Quarterback John O'Korn threw for 198 yards and a touchdown and Kenneth Farrow ran for two second-half TDs. O'Korn was just 13 of 30, but found a favorite receiver in Deontay Greenberry, who caught four passes for 76 yards.
Houston trailed 15-10 midway through the third quarter but rallied to drop Memphis to 1-4.
Buzzwords on jerseys
The Cougars wore words representing their core values Spirit, Tradition and Honor – on the backs of their jerseys, instead of their surnames, for the first and only time this season to commemorate homecoming. "The words have been assigned randomly," BYU noted in the press notes distributed before the game.
Former BYU receiver Tyler Anderson (1988-93), now Orem High's head football coach, carried the alumni flag onto the field. Senior linebacker Austen Jorgensen carried the team flag out and punter Scott Arellano brought out the special teams flag.