You can possess the mindset of a winner before actually winning... in fact, most winners develop that mindset long before they actually win.
that's where Casper's "process" comments are somewhat valid. Winners do the right things everyday, and understand that the outcome in any given moment won't necessarily reflect the quality of process, but over time doing things the right way sets you up for success.
Any GM can and should only speak like a winner. Babcock and Shannahan certainly did from day one in their jobs, and matched with the discipline and ability to actually walk the talk, surprise surprise, they are on their way to building one hell of contender. *edit- sorry, bad example since Babcock obviously has won before, though shanny hasn't in his current role... but I can pull you a list of people from various places who talked the same way before winning and after being validated by winning (Sutter comes to mind quickly in the hockey world... Tomlin, Carroll, Belicheck in the NFL, Kerr in the NBA, Guardiola and Ferguson in the soccer world and on and on. people's whose mindset and narrative shifts after winning are more often then not products of circumstance vs process.
We have a GM that talks like a loser (excuses, defensive, finger pointing, inconsistent), and manages the team in pretty much the same way... no plan, no vision, no consistency.