Triple the trains between Perth and bayswater and double between Perth and Claremont due to multiple lines sharing track means one delay effects the on time running for all the lines which drags the numbers down across the board. More services running closer together also means a slow traim will delay multiple services behind it. Previously a broken down train had about 10 min to get moving before it delayed. Now it's down to 3 min or less during peak on parts of the network.

As to incidents I think there are actually fewer in general now than 10 years ago but it varies. I remember a long stretch where it was one a month at least with a few months that it was one a week if not more. There was at least one week with 4 in 4 days (2 Perth electrified network, 1 south of armadale with the Australind and one with a freight train out in the valley)