'Bottling it' or underperforming in an important game of cricket is all very suibjective. Anderson bowled brilliantly under the pressure of Ashes deciders in Melbourne and Sydney this winter and poorly in two test matches you have highlighted. Its a facet of every cricketer that has ever played the game that they play well sometimes and badly on occasions. Anderson's record is avery good one and he has played excellent, consistent cricket for a long time.
Broad for example has bowled poorly for England more often than not and has a poor record but as he has been carried by a winning team led by Anderson we can afford to be patient with him.