100% spot on. Passing range and vulnerability to press are vital areas of improvement.Fernandinho is by no means the perfect player in that position. His longer passing isn't great, he's vulnerable to the press and defensive positioning is temperamental. He's one of our best players but there's a lot of room to improve on some areas of his game that would make a big difference.
Part of becoming a better team is improving even where you're strong and I would expect any defensive midfielder we bought to be seriously challenging Fernandinho next season with the aim of he new person developing into a better player than Fern is now.