Looking back at December I really think it was the Arctic domain that screwed us more then anything. There was so much excitement for blocking and a negative NAO, but I think the structure and placement of the anomalies hurt us. I think if we had seen these anomalies farther to the north and east we would have been smoked the second half of the month. I guess you could argue having the height anomalies in the GoA farther east too.
But look at the 10-20 and then 20-25. If that block is farther east the trough axis is shifted east and more favorable for us. IIRC, there seems to be a lot of optimism for a west-based NAO block, but IMO, an east-based is what we really want. When you get west-based (and displaced south) with a strong anomaly, you're playing with serious fire and risking higher height anomalies extending into our latitude.