As a Tiger fan throughout the Dombrowski era, I'm not happy to see him leave. He took a team that had gone over a decade without a winning record and made it into the winningest team in the AL the past 9 years.
People point to the Prince Fielder contract, but that is not on him. Before Fielder signed, Dombrowski said he wouldn't be a good fit. Scott Boras than calls Mike Illitch, Illitch has an emotional attachment to Prince since Cecil played in Detroit and Illitch knew Prince since he was a kid. Prince Fielder was an Illitch signing.
There's also the Cabrera trade, The Granderson and Edwin Jackson trade that netted them Austin Jackson and Max Scherzer, He traded Ramon Santiago for Carlos Guillen, Ugeth Urbina for Polanco, a minor leaguer who never made the bigs for Peralta. He traded Porcello for Cespedes and then flipped Cespedes for a decent pitching prospect. He picked up Iglesias for a replacement level OF. He also plucked JD Martinez off the scrap heap. Dombrowski was rarely on the wrong side of a trade. It's also hard to fault him for the Verlander extension since he was coming off two Cy Young caliber seasons and an MVP.