I think its a common enough reaction for a young player who is under pressure and in a bad run of form, they dont have the confidence to go and assert their game properly so through a combination of frustration and wanting to be able to have some/any impact on the game. People will more often criticise a player for pulling out of a tackle than going in too hard so the pressure is on them to make that tackle or be written off as 'total lightweight cunt' or whatever the phrase of the day is
And anybody who calls his tackling reckless would do well to remember Gerrard at the same age, I used to wince watching him go into a 50/50 challenge. Im not saying Shelvey is as good a player but I see the attitude as similar, the need to impress and prove yourself, the frustration when things are going against you. Gerrard was too good to leave out of the team on those occasions but Shelvey isnt, I think he needs to be carefully managed, and to be fair Rodgers had removed from the spotlight recently, maybe last night with the atmosphere at boiling point and us on the verge of historic result it was a little too much for somebody of his temprement, but I would take a young guy who comes on and wants to get involved over somebody who hides from the ball every day of the week