If you had a starting IX (nine) you'd be two players short - that won't have helped! ;-)

More seriously, he might have been playing with attacking wide players, pressing on into the gaps behind your wide midfield players and even have fullbacks supporting them. IRL, three centre backs often struggle with 1 striker because with all of them in the centre and only one player to mark there is space elsewhere on the field

What rating did your keeper get? I played a game the other day with a keeper on very poor morale (stupid oversight) and lost 3-1 despite having about 10% more possession and twice as many shots as the other team