Twins- Is Gardy's strategy not working anymore?

So, as the Twins play the Nationals tonight, I'd like to talk about manager Ron Gardenhire. He has had lots of success since he was hired in 2002, leading the Twins to a 958-882 record, good for a .513 winning percentage. At first glance, this indicates that Gardenhire can consistently win games, and that makes him a good coach. However, there are two weird stats that are worrisome for his coaching future.

Number 1: Playoffs

Gardenhire is 6-21 in the playoffs. This is a fact that is well known by Twins fans across the state, and has led to a belief in a jinx of sorts against the New York Yankees. However, it isn't because the Twins just magically can't beat the Yankees. It's due to the fact that it's in the playoffs. This has to do with Gardy's management and team-building style.
Have you ever noticed that sometimes, when the Twins face a pitcher like Justin Verlander, that Gardy tends to rest players such as Joe Mauer? Look for it from now on. It happens quite a bit. Take this afternoon's 7-0 drubbing by the Nationals. Jordan Zimmerman was pitching, and he now has a 2.00 ERA, which, in most people's minds, makes him an ace and a vital member of the Nationals' rotation. So, Gardy did his usual switch and rested Joe Mauer, Josh Willingham, and Jamey Carroll. Naturally, the Twins didn't even score a run. However, this is a great strategy for winning games at a decent rate in the regular season, as it means your players are fresher, healthier, and have a better chance to win games against less dominating pitchers.
But, if you look at the playoffs, players are almost always well rested, and it's hard to give games away in the playoffs, especially against high-tier competition, so Gardy usually enters the playoffs against players with more talent, but the important difference here is that both teams have well rested players and benches, so the Twins usually end up losing in the playoffs, and that means the season ends in a failure, and usually with a first round exit. There is a point where this just can't be tolerated any more, and that may be approaching.

Number 2: Recent Seasons

Gardenhire has gone 156-226 since 2010, his last playoff year, and that could be a sign that his strategy just doesn't work as well anymore. Pitchers have progressively gotten better over the past few years, and there have been many new aces introduced to the league in the past couple years. These guys include Stephen Strasburg, Yu Darvish, Matt Harvey, Michael Pineda, and Chris Sale. Due to more dominating pitchers, Gardenhire can't employ his strategy as much, as the guy the next day might be just as deadly, so he has to decide to play players both days, eliminating the rest factor for his team, and making the Twins play just about as well as expected.

These points don't necessarily mean Gardenhire should be fired, but it does mean that he may have to change his management style to continue his success with the Minnesota Twins.