Yes they happened but so did CMS take a poor penalty to drop two points v Leeds, ditto Ulloa later, Barnes self destruction at Sheff Wed when we could have got at least a point, wasn't it Hull at home where Kuszczak made a brilliant save to which we got 3 points from.
However, a goalkeeping error can/will always lead to a goal, a striker can miss 10 chances, a poor penalty miss can cost the same points as a goalkeeper error. On the other side of the coin, how many points have our keeper won this season.