The answer is unfortunately ... it depends ..

The only way you can tell for sure if it was competitive is by watching the video.

As a few guidelines 5 lengths is the norm was a competitive run but its going to depend again on where 3rd place was. A loss of 5 lengths and 3rd running in at 4.5 lengths is a competitive run but a loss of 5 lengths and 3rd running in 1 length behind the winner is not so competitive.