It's no secret that Alaska's on-time record during winter months leaves much to be desired. December and January are generally the worst months due to weather-related issues, and the shorter, "optimistic" turn times implemented last year certainly haven't improved the situation. It's common for afternoon/evening runs on certain routes to be 30+ minutes delayed due to an accumulating of shorter delays throughout the day (Southwest has this problem too). I have to wonder if the gate agents/crew tire of offering explanations during periods when so many flights are delayed. Some of the longer-delays are weather-related, although many seem to be "mechanicals". I think it is less that AS has more mechanicals compared to other airlines than that Alaska's high aircraft utilization/lack of spares leads to a pronounced domino effect.
I think AS could probably do a better job with expediting delayed flights. The turn times at the outstations are pretty good, but SEA is usually slow in my experience. 30 minute turns might work at SJC or BUR, but I think they should increase to a minimum of 40 min ground times at congested airports such as SEA and LAX.
AS made a lot of progress with on-time performance in recent years, but unfortunately it has slipped during the past six months. Hopefully they can get back on the right track.