Very simple. The loads may have been healthy, but the yields weren't. Majority of pax ex-Manchester were low yielding tourist traffic.
I'm not sure I'd go so far as to say MAS are in serious financial trouble, but they've certainly realised that they're living beyond their means. As a result, some international and domestic routes are being chopped, they're selling their KL headquarters and there are even doubts as to whether they'll go ahead with their A380 purchases. Sadly, as a recent passenger, I also get the impression that quality of in-flight service has deteriorated (been reduced?).