Yagiello chose to pass on professional baseball and accepted a football scholarship from The College of William & Mary. As a true freshman, he appeared in 3 games as a backup behind Chris Garrity, before being redshirted. As a redshirt freshman in his first college start against Miami of Ohio Stan threw for 414 yards with 2 TD passes. After an injury in week 3 he platooned at quarterback until the sixth game of the season against Dartmouth College, when he took over the regular starting role. As a sophomore, he had 18 out of 28 completions for 236 yards, 3 touchdown passes and one rushing touchdown, in a 28-12 win against the Virginia Military Institute. As a junior, he had 261 completions out of 428 pass attempts for 2,801 passing yards. As a fifth year senior, he had 240 completions out of 413 pass attempts for 2,962 passing yards, 23 touchdown passes and was ranked 11th nationally in passing efficiency. He made 24 completions for 405 yards and 2 touchdowns, in a 31-14 win against James Madison University. He had 345 passing yards against Norfolk State University. He finished his college football career as the first four-year starter in school history. He also set career school records with 737 completions out of 1,246 pass attempts for 8,249 passing yards, 51 touchdown passes and twenty 200-yard passing games. Yagiello also played college baseball, leading his team with a.437 batting average and a.470 on-base percentage as a junior in 1984. In 1997, he was inducted into the William and MaryAthletics Hall of Fame.
In June 1987, after his release from the Argonauts, Yagiello signed with the Montreal Alouettes. He was released after Montreal withdrew from league due to banktuptcy.
Pittsburgh Gladiators (AFL)
On July 6, 1987, he was signed by the Pittsburgh Gladiators of the Arena Football League, to replace backup quarterback Kevin Russell.
After the NFLPA strike was declared on the third week of the 1987 season, those contests were canceled and the NFL decided that the games would be played with replacement players. On September 21, he was signed to be a part of the Dallas Cowboys replacement team. He was a backup quarterback behind Kevin Sweeney, Danny White and Loren Snyder. He played in one game and was cut on October 7.
New York Knights
In 1987, he was signed by the New York Knights of the Arena Football League to be the backup quarterback. He was released on June 2, 1988.
