I am a fairly predictable person; people who know me, even those who know me not really that well, can quite accurately predict what I will do under different circumstances. For example, everyone can predict correctly that I will try to be the first one to ask the speaker questions after a talk. I am also a fairly reliable person; if I agree to do something, I will usually get it done and get it done on time.
So, can I be described as predictably reliable? Well, that sounds redundant, for my being reliable implies that people can quite accurately predict that I will do what I agree to do. How about being reliably predictable? This is redundant too if it means "can be predicted correctly most of the time". There is another sense in which it is redundant: given that I am predictable, people obviously can rely on their prediction of what I will do.
Being predictable and being reliable, however, are not the same, at least for the reason that a person who is predictable may not be reliable. Indeed, a person can be predictably unreliable. Isn't "predictably unreliable" redundant too? No, for a person who is unreliable is not a person who always does not do what he has agreed to do, but a person who does not always do what he has agreed to do. That is, sometimes he does, sometimes he does not. If this makes such a person unpredictable, then perhaps we can call him "predictably unpredictable"!