Four summers ago, the Astros installed a revolving door at Minute Maid Park. Fans watched with chagrin and dismay as player after player moved on. _Some fans were in disbelief while others recognized the house-cleaning was necessary to start the new era. Still, the past three summers have brought heartache, angst and frustration. Now, finally, Jeff Luhnow is faced with the dilemma of a question: Leave the revolving door intact or update it with a more fundamental approach that moves away from the annual sell off ritual while keeping in step with the overall blueprint._ Since 2010, the Astros have made more than 20 trades during July and August, some [...]