I'd much rather take a chance on an up-and-comer. Not only is Wannstedt 60 years old, but he was a mediocre NFL coach, and an average college coach.
Too many people here only look at records rather than situations (leading to absurd conclusions that coaches that took over 1-10 programs were bad because they only went 6-6 the first year), but in Wannstedt's case, he actually took a good situation, brought in outstanding recruiting classes, and still managed to fail at Pitt.
Walt Harris went to 5 straight bowl games at Pitt and seemed to routinely finish in the 7-5 to 9-4 range in his last few seasons. After taking over for Harris, Wannstedt missed a bowl game in his first three seasons, with two losing seasons and a 6-6 season. He made bowl games in his last three seasons but was far from impressive, particularly given his great recruiting classes, with a 10-3 season and a visit to the Meineke Car Care Bowl being the highlight of his tenure.
10-3 might not seem to bad, but it was rare, and he was routinely bringing in the top recruiting classes in the Big East, but couldn't win the conference. If you look on Scout, he actually had a few top 10 classes, and was routinely in the top 25 (which is great for the Big East). He should've been winning the Big East every other year and played in a few marquee bowl games with the talent he amassed. But instead 6-6 and 7-5 were the norm.
I'm not opposed to an NFL coordinator, but Wannstedt has been at best, an average head coach.