100% agree with this. Our best performances have been with Kopy in the backline with Taylor, and Durante. Doyle just doesn't offer as much as Kopy in that position.
Food for thought - defensive trios obviously aren't the sole factor with regard to the number of goals conceded and these are small samples.
Doyle, Durante, Taylor - v NEW 1-0, @ BRI 0-0, v WSW 0-3 ... v BRI 4-1, @ MVC 1-1, @ ADL 0-0, @ WSW 3-2, V CCM 3-2
Fox, Durante, Taylor - @ MCY 0-2
Durante, Kopczynski, Taylor - v ADL 1-3
Kopczynski, Durante, Taylor - v PER 1-1, @ SYD 3-1, v CCM 2-0
Doyle replaced Kopczynski at halftime v CCM the first time so...
Doyle, Durante, Taylor - 9 goals conceded in 8.5 matches, six in 5.5 since they came back together v Brisbane at home
Fox, Durante, Taylor - 2 goals conceded in one match
Durante, Kopczynski, Taylor - 3 goals conceded in one match
Kopczynski, Durante, Taylor - 2 goals conceded in 2.5 matches
Four defensive combinations (it's the same number if you add the wingbacks into the mix - the two matches where it wasn't Fenton/Cacace were the two where it was a one-off back three) in 13 games compared to nine in 13 last season (and 18 in 27!).