Who is he?
Villanueva is a 28 year old right-handed pitcher who made his major league debut in 2006 with the Milwaukee Brewers. He amassed a 20-24 record and 4.34 ERA in five seasons with the Brewers before being traded to the Blue Jays in December of 2010. Villanueva improved slightly in the past couple seasons, going 13-11 with a 4.11 ERA with the Blue Jays in 2011 and 2012. He has struck out nearly 8 batters per 9 innings throughout his career, but his strikeout rate has varied quite a bit from year to year.
Why should we care?
Villanueva would be a cheap option as a 5th starter who could be a strikeout machine if everything goes well. In 2010, he struck out 11.4 batters per 9 innings. The caveat? He only pitched 52 2/3 innings in the big leagues that season. Still, he struck out almost a batter per inning last year and a move to a larger home ballpark* may deflate his high home run rate. For a pitcher who has increasingly relied on fly ball outs over the past couple years, this could be a huge boost.
*Note: Park factors see the Rogers Centre and Comerica Park on level ground, but the CoPa's dimensions are much deeper everywhere except the power alleys, where Rogers has a 5 foot advantage. And with the defensive outfield the Tigers have now, there won't be any cheap base hits to be had in Detroit this season.
Why should we stay away?
Villanueva has never pitched more than 125 big league innings in a season. This is largely because he had been pitching out of the bullpen until being thrust into a starter's role due to injuries in June of 2012. As a starter in 2012, Villanueva was just 5-7 with a 4.50 ERA in 92 innings. Someone that hasn't even been able to crack the rotation in Toronto or Milwaukee is just begging to be replaced by any of the arms the Tigers currently have in their system by mid-May if things don't go well.
While the strikeouts are kind of nice, Villanueva's other peripherals aren't so appealing. He walks more than three batters per nine innings and has allowed 1.31 home runs per 9 innings throughout his career. Last season, he allowed home runs at a Joaquin Benoit-like 1.65 per 9 innings clip.
Will he end up in Detroit?
Frankly, I'm not sure how or why Villanueva's name was mentioned in the comments as someone we should pursue. He's a glorified long reliever who hasn't put up great numbers during his multiple chances in a big league rotation. Sure, he would be a cheap option in the rotation, but so would Duane Below, Adam Wilk, or Casey Crosby. You will probably get the same results out of any of those four. No thanks.