Kangaroos hard man Glenn Archer admits the days of going in and crashing opponents with their head over the ball are over following the AFL tribunal's tough penalties for head-high contact on Tuesday night.Geelong's Mathew Stokes and Fremantle's Michael Johnson became the first players to be suspended under the league's new crackdown on front-on contact in bumping collisions with both outed for four matches.And even Archer, the player who has faced the tribunal more than any other current player and who is renowned as the game's toughest player, has got the message."In years gone by if a bloke was over the ball, you would just go for the ball and if you hit him in the head, bad luck," he said on Wednesday."But now you really have to think about it because you see what sort of suspensions they can hand down so it's at the forefront of your mind when you are going for the ball that you don’t want to hit someone in the head."Archer admitted he was surprised by the penalties, particularly the one for Johnson with his incident occurring against the Kangaroos last Sunday."They're pretty tough penalties, the Michael Johnson one it looked like he just turned his back but they are the rules now and we have got just to play by them."Archer said the modern-day player had far more to think about on the field than when he began his career in the rough and tumble early 90's."That is just a given because of all the interpretations and the added rules so you do have to think a lot more when you are out on the ground," he said."If you are going for one on one contests you are thinking don't hit his arms, don’t get in his back and it's something you have just got to adapt to."Archer admitted he struggled to recognise the modern-day game from the one in which he began his career 15 years ago but said it was all part of the game's evolution."It is different, but I'm sure the blokes that played in the 1960's would have said the same thing about the 90's. Each decade things are going to change and you have just got to adapt to it."But while Archer has long been a critic of some of the game's recent changes, he is surprisingly unfazed by the new stricter interpretation regarding hands in the back even though many coaches believe the rule is unfair on defenders."It's been good for me, I actually got a free kick on the weekend," Archer said of the rule change."Someone pushed me in the back so I have got nothing to whinge about yet, and I actually used it (the new rule) as a bit of a tool on the weekend (against Fremantle).""I was playing loose man in front of (Dockers' star forward Matthew) Pavlich and the ball got kicked back over my head and I knew if I pushed back hard enough he was going to have to put his hands in my back.""So, who knows, it might be an advantage for the backman so let's let it pan out and see what happens."