As a Tigers fan who has watched Dombrowski his entire career with the Tigers, I will say he rarely comes up on the wrong side of a trade. Yes the Tigers have traded many prospects, but rarely did this prospects amount to anything. Yes the Tigers farm system was always near the bottom of the league but the Tigers always managed to trade for the players they needed. There was also a lot of pressure from ownership to win a title. Dombrowski took a 119 loss team and had them in the World Series in three years and a perennial playoff contender. He also has a knack for finding players on other teams who were underwhelming and making them into stars like Guillen, Polanco, Peralta, Edwin Jackson, Fister, Iglesias, JD Martinez to name a few. He also traded for Scherzer before he was elite, got Cabrera for nothing, and was able to dump Fielder's salary and get a 5 win player. The Fielder signing was all Mike Illitch.
Downsides are the complete inability to build a respectable bullpen. For the most part, the Tigers had a decent closer but it was nauseating relying on the likes of Joba Chmberlain and Tom Gorzelany heading into the season. This despite the fact he has drafted a number of relievers in the first round who have never amounted to anything. His drafting has not been great but he is great at trading prospects before they lose value. I think Dombrowski is the perfect guy for a team with a big payroll who wants to contend. He has also proven he can rebuild teams in Florida and Montreal as well.