If Dota 2 is something you focus on and approach it seriously by studying replays/builds, it isn't. If you play other games and play a game here and there, it really is. Experience plays a huge role, if you play a new hero, you have to focus a lot more on what you are doing than what is going on on the map elsewhere. First game after a week of not playing usually goes terribly, since my game sense is off and I'm feeding a lot. Sometimes it's the "space created" kind of feeding, but I know I'm just being bad. Really, the best way to climb MMR is to pick 4-5 not very flashy heroes and focus on being in the right place at the right time, drop any kind of negative attitude and being readyy to adapt to whatever the game brings.
Yesterday I had a game with terrible QW invoker mid who got ganked several times in mid and his sole objective in the game was buying orchid/bloodthorn 30/40 minutes in and chasing kills on any of their overfed heroes, which didn't go very well since he missed his timing entirely and there was fat storm fucking us all. You can't win 4v6 by flaming him, but 4v5 is not entirely unheard of since their major carry was a storm who I was able to shut down quite well with kotl in fights until he got bkb as a 4th item. We still lost though, but it was a lot closer than it had any business being.