Lack of planning is out of any coach, the problem with some of them is incompetency for the game and lack of strategy. You know Premier League is one of the watch league in the world and been available as one of the coach automatically makes you popular, makes you available for other opportunities. What some of them want is fame yet they lack the qualities to be there, you want to represent a big club yet you don't have what it take to help them win the league.
Some coaches thinks that once they have world class players, their team must perform well not knowing that their extra effort is needed to make the players play well especially in the Premier League where there tough competition among all the teams including bottom teams.
Coaching a big team in the Premier League is a great opportunity for any coach to show and express his talent ahead further managerial jobs even after leaving the Premier League teams; Antonio Konte, Sari, and others are good example because they both do their best while coaching Chelsea which is why they are still been offered some jobs despite their age.
Look at Lampard for example, he was a good players and was well respect, had a good time in Chelsea but loo at his career since he signed up been a manager, he has never achieved anything serious in his career, this is to say not all great players make good coach and not all good coaches were once a player in their life time. There are some of them that never play for any club and yet they are good because to coach is another talent on it own.
The way Alonso did is better for retired players than starting their career in the Premier League. Lampard was a great legend in the heart of Chelsea fans, but his attempt towards managing the team because of the passion and love he have for the team has affected his reputation to the extent that some fans forgot all he did for the team and he was been accused for letting the team down; therefore, as a retired player willing to go into managerial work, avoid starting your career in the Premier League.