Going to break down each playoff game into which of 6 reasons why, in my opinion, it was won. Reasons being "individual play", "team composition", "objective calls/vision/preparation", "laning phase", "teamfighting", "rotational play (includes splitpushing and poking/sieging)". Individual play includes games won due to mistakes (e.g. Woolite getting caught recalling in Roccat/CW at ~42mins) and due to item build errors.
Game 1: H2K v CW
Won because H2K controlled objectives extremely well (4 dragons at 26 mins, all outer towers early, rushed baron) and Ryu played very well on Ahri, especially when Hjarnan got caught out.
0.5 to "individual play"
0.5 to "objective calls/preparation/vision"
Game 2: CW v H2K
CW won the laning phase hard, with a big edge in bot lane, peaking near 100cs, a solo kill in top lane and a kill on H2K's jungler. Kalista/Annie soon began jumping on to Kog'Maw whenever he came to lane and CW got multiple turrets and dragons with their advantage, leading to a 7k gold lead at 25 minutes. forcing desperate engages from H2K, who teamfought well and hung in. I think there may have been a compositional edge for CW in this game, since their comp had a ton of dive potential against a fairly unprotected Kog'Maw (give or take Lulu support), but they never took advantage of it since they teamfought poorly, not pressuring Kog'Maw. CW's vision control and an aggressive baron call got them ahead again, but the game was won by H2K's superior teamfighting, twice engaging on CW while they were grouped at dragon and getting to Freeze quickly and decisively.
1.0 to "teamfighting"
Game 3: H2K v CW
H2K's bot lane falls behind again, but Loulex sneaks a dragon, taking advantage of poor vision control from CW. CW pull further ahead with continued good laning and get first blood on Maokai. Unfortunately, Soren gets solo killed by Ryu and H2K quickly turn that into mid outer and second dragon, pulling them significantly ahead in objectives. H2K dominate the game from then on, reading Airwaks' gank on top lane and turning it 2-0 by having Sejuani and Zed collapse on it. Maokai TPs bottom and double kills the bot lane, before Airwaks walks in blind to his jungle and dies again. Putting this down as objective control/vision/preparation and not rotations as I think it happened more due to reading CW's plays and blind spots, made possible by Ryu's huge advantage, than a conscious plan from H2K. Airwaks later ults Sejuani to start a stupid teamfight which ends the game as a contest.
0.5 for "individual play" (partly Ryu, partly Airwaks' tilting)
0.5 for "objective calls/preparation/vision"
Totals:
1 - Teamfighting
1 - Objective calls/preparation/vision
1 - Individual play
One-sided victory by H2K, though it could've been very different if CW didn't throw away their lead in game 2 with sloppy teamfights.