If you want to look at a good stat of coaching effectiveness, it's a team's win-loss record in close games. For this purpose, I define close games as those won by five points or less. It's an arbitrary standard, but if game is that close it indicates that one or two smart plays down the line could have won the game.
When it comes to drawing up those plays, success depends not only on the players but on the coach drawing up the plays. Furthermore, it comes down to how much players trust their coach during crunch time. In the documentary Training Rules, one of former Penn State coach Rene Portland's players suggested that the reason the Lady Lions continually faltered in the NCAA tournament was that there was a lack of trust between the coach and the players.
Here are the stats in 2013 for games decided by five points or less:
|Games Decided by Five Points or Less|
Even though New York leads this stat , Washington is second. Furthermore, they have played 10 games where the winning margin was just five points or less by either team. This is almost half of their total games played - 10 games out of 21 as of this writing. This is also four more close games than any other team has played - San Antonio is 3-3 in six close games.
You could almost call them the Cardiac Mystics. Close games isn't a be-all and end-all metric - there are other factors besides close games where a coach's influence can be inferred - but it's a great testament to Mike Thibault as well as to the entire Mystics team.