Serious question: do you believe Man Utd to be the second best team in the league because they won something that wasn't the league: The Carabao Cup? To win that cup they won 5 games against Villa, Burnley, Charlton, Nottingham Forest and Newcastle (3 premier league teams).
The premier league table contains the strongest teams in the country and is literally there to illustrate the position of the teams who have done 'the best'. Are Utd really second best in the league because they had less success over the year against the 20 best clubs in the country but won a knockout cup against weaker opponents?