This is where we need help from sales operations. They should have a method for keeping track of what is in the sales funnel. They should have a method of keeping track of when a deal is won or lost. Contact information from wins and losses should be forwarded to product management for win/loss interviews. When you have multiple products involved in a complex deal, product managers can take turns conducting the interviews. 

Having an sales force automation system that would send out an alert would be ideal. In the absence of this, someone should keep a spreadsheet and update it once the interviews are done. You don't want multiple product managers calling the same deals ("Don't you guys talk to one another?").

The best thing to do to get started is to do a pilot project. 5 wins and 5 losses. Work the kinks out in the processes you will use to inform people about whom to interview and when. Make sure the interview gets recorded somewhere so the information can get aggregated and analyzed.

Answered by Barbara Nelson