The system, basically, is to either outscore or outsave your possession stats.
Over the last four full (82-game) seasons, seven teams have made the playoffs with a CF% below 48. All but one did it through amazing goaltending, amazing shooting, or both:
Code:
Season TM CF% Sv% Rk Sh% Rk
2013-14 COL 46.9 .930 ( 6) 8.80 ( 2)
2013-14 MTL 46.7 .930 ( 5) 7.44 (21)
2011-12 NYR 47.7 .927 ( 8) 8.30 ( 8)
2011-12 NAS 46.6 .925 (12) 8.51 ( 6)
2010-11 ANA 44.4 .923 (16) 7.79 (20)
2009-10 MTL 47.2 .929 ( 3) 7.58 (25)
2009-10 COL 44.8 .926 ( 8) 8.84 ( 4)
2014-15 CGY 44.8 .922 (16) 8.88 ( 2)
(percentages and ranks at 5 on 5, per hockeyanalysis.com)
That Ducks team in 2010-11 had no business being anywhere near the post-season...
Montreal is the poster child for the system that defeats Corsi. It's called "Have a gold medal winning goaltender". The Habs are 21st in CF% this year at 49.4, 26th last year at 46.7, 7th in 2012-13 at 52.8, 22nd in 2011-12 at 48.0, 11th in 2010-11 at 51.6 and 27th in 2009-10 at 47.2%.
Goaltending is reasonably predictable from season to season, so it can consistently overcome poor possession. Calgary is in a playoff spot because of shooting percentage, and honestly, it is far more random. Washington, for instance, has ranged anywhere from 10.3% to 7.6% between 2009-10 and this season. And a 3% swing on 1800 shots is 54 goals. They are an extreme though.