Krakow didn't commence until 17th June 2013 so the numbers for last month would show a large increase.
The feeling seems to have been that SEN-KRK was harming LGW-KRK loads/yields so that is why it is being dropped. The June figures show LGW-KRK to have had a small increase in pax numbers but the yield may be lower perhaps than before the SEN route started.