CaptainRook said:
….the key thing I learned from practicing TIE Fighter formations, is that they will often trip up over each other when they turn. You have to make your opponent get greedy with them.
It gets a bit more complicated if there are other ships following behind, but it's still not terrible. Problems are kept to a minimum if you make sure pilots with higher skill are generally placed at the back of the formation, so that you can move fighters in order from front to back. It also helps to remember not to get greedy, if you're the Imp pilot: staying in formation is probably better than going for that perfect killshot, because the shot isn't worth it if it causes a 5-TIE pileup in an asteroid field.
(One good reason to field Biggs is the look on the Imperial player's face when he realizes he destroyed his formation in order to get that perfect Rng 1 killshot on Wedge… and then is forced to take a Rng 2 obstructed shot against R2-F2'd Biggs anyway.)