Attack in the middle
Attack in the middle (AIM) is one of the game's tactics. It raises the probability that a chance is created in the middle of the field by at least 20%, lowering at the same time the probability that a chance is created on the wing. The ability in the tactic is calculated by summing the Passing ability of all outfield players. When calculating AIM skill, an experience bonus is added for each involved player.
The only unique drawback of the AIM tactic is a weakening of the wing defence.
However, as with all predictable formations and tactics, if you use AIM all the time, don't be surprised when the opposition stack the central defence against you.
There is much debate as to the distribution of chances. One common theory believes the distribution of chances between left wing, center, right wing and set pieces (including penalties) is 25%-40%-25%-10%. Playing AIM would change this distribution to something like 21%-48%-21%-10% (if the ability in the tactic is low) or to 17%-56%-17%-10% (if the ability in the tactic is the highest possible).
However, as Hattrick has never stated the actual chance distribution, AIM's true effectiveness is not known. Note that Hattristics reports (as of 06 April 2006) the chance distribution (excluding counterattacks, special events, and penalties) as 41.3%-25.65%-25.65%-7.4%, although these numbers may be skewed by differences in tactics, attack, and defence ratings.
The AIM tactic is not reported with events like counter-attacks, and lost opportunities are detailed only for the tactics above. The only indication that a player is using AIM is at the start of the game report and in the match ratings. The game, however, keeps adding a modifier throughout the match.