LTNman
I agree that at first sight the headline is open to the interpretation that SEN's total passenger numbers have increased by 300%, rather than being just the number of Flybe passengers that have done so. So maybe a bit of 'spin' there.
However the first bullet point in the article says "...... up from over 8,700 in April '17 to over 35,000 in August '17." so it's quite clear how the comparison is being made. Interesting also that 163,000 seats have been sold on the new routes ".... in addition to existing existing ATR turboprop services.".