Croyle took further advantage of the second-team defense with the second-longest play, a 27-yard strike to Zeke Knight on the next play taking the ball to the 17-yard line.
Two plays later, on Croyle's fourth pass attempt of the day, Walker lined up at the usual tight end spot, but motioned across the formation split wide to Croyle's left where he ran past the cornerback's zone coverage and caught a well-timed 17-yard touchdown delivery from Croyle before the safety could get close to the play.
Most of Croyle's completions came down the field. He hit Knight on a 20-yard perfect pass to the right sideline after scrambling on third-and nine.
Alabama Head Coach Mike Shula started the offense in a hole, backing the first unit up to its own seven-yard line to open the scrimmage.
The second drive began on the one-yard line, but Tim Castille quickly gave the offense breathing room with a 22 yard run.
Croyle finished the day 10-for-15 passing with three touchdowns.
Marc Guillon looked sharp in perhaps his best day of fall training camp, completing four-of-nine passes for 40 yards, including two touchdowns.
John Parker Wilson completed just one-of-six passes for a loss of a yard.
True freshman Ali Sharrief was quick and carried a low center of gravity in his first scrimmage work since rehabilitating from shoulder surgery in the late spring. He hauled in a Jimmy Barnes pass for seven yards on his first touch. Sharrief had three carries for six yards in the scrimmage, adding a two catches for eight yards.
Tyrone Prothro streaked by scout team coverage units for the second practice in a row, scoring Tuesday on a 75-yard punt return, highlighted by a Terrence Jones peel-back block, knocking a scout-team off his feet.
Jeremy Schatz was not at the stadium Tuesday. Shula said Schatz had a sore leg requiring attention.
Ryan Saxby missed his only field goal attempt which came from 34 yards away. The ball had the distance, but pinged off the right upright and fell away.
Jamie Christensen made a 44-yard field goal attempt, but missed a 43 yarder at the end of the scrimmage that also hit the right upright.
Defensively, Chris Keys led the way with five tackles, most of which came on running plays. DeMeco Ryans also had a nice three-tackle day with a big fill and hit on Roy Upchurch for a loss of a yard on a first down play.
Hall snuffed out a flat pass play to fullback Ryan Morrow on third-and-11, standing Morrow up moments after the catch for no gain.
The most unlikely pancake block of the year was on Keith Brown's reverse run, which was stopped for no gain. Brodie Croyle got out in front on the play, using perfect blocking technique to put a lightly-treading linebacker onto the ground.
Passing (Comp-Att-Yds): Brodie Croyle (9-14-130, 2 TD); Marc Guillon (4-9-40, 2 TD); Jimmy Barnes (3-3-8); John Parker Wilson (1-6-minus 1)
Tim Castille (2-27); Roy Upchurch (6-24, TD); Jimmy Johns (6-22); Glen Coffee (6-10); Kenneth Darby (1-6); Ali Sharrief (3-6); Le'Ron McClain (1-3); Theo Townsend (1-2); Keith Brown (1-0, on a reverse play); Marc Guillon (1-minus 6); Jimmy Barnes (1-minus 3); Brodie Croyle (3-minus 15);
Zeke Knight (3-53); Nick Walker (2-57, TD); Matt Caddell (2-28, 2 TD); Tyrone Prothro (1-19, TD); Ali Sharrief (2-8); Matt Miller (1-6); Rashad Johnson (1-6); DJ Hall (1-2); Glen Coffee (1-1); Ryan Morrow (1-0); Roy Upchurch (1-minus 1);
Chris Keys (5 tackles, TFL); Marcel Stamps (3 tackles); Prince Hall (3 tackles), Charlie Peprah (3 tackles); Bryan Kilpatrick (3 tackles); DeMeco Ryans (3 tackles); Mark Anderson (tackle, sack); Terrence Jones (tackle, sack); Chris Harris (tackle, sack); Lorenzo Washington (tackle, sack); J.P. Adams (tackles); Marcus Carter (tackle); Lionel Mitchell (tackle); Brandon Fanney (tackle); Freddie Roach (tackle); Juwan Simpson (tackle); Wallace Gilberry (2 sacks, QB hurry); Rudy Griffin (tackle); Matt Collins (2 tackles); Cory Reamer (tackle); Schreiber (tackle); Jeff Dukes (tackle); Anthony Madison (PBU); Juke King (tackle); Jeremy Clark (tackle)