Read the bit around it that. In relation to where we were this time last week, being heavy favourites for 4 competitions then yes only winning the league is underwhelming because there's an opportunity for significantly more.
Just like last season when the scousers looked like winning everything and having an unbeaten season at one point and then ended the season with just the league, despite waiting 30 years for it, many were rightly putting that down as an underwhelming season for them because of what they should have won. The same applies here.