Well, in my opinion the DBAs are the poorest of poorest guys – No, no, no… I am not talking financially here 
. If there is an performance issue in the application, the first thing they do is to summon the DBA incharge and ask him to look “whats going on” in the database. They stop thinking about the other tiers – these days its quite common to find a 5 tier 6 tier application. Their “instinct” tell them to look “something” in the database.
Especially people with a “bit” of oracle knowledge start sitting on DBAs head and firing questions after questions
“Have you run the statspack report?“
“Can you put the trace on and see whats happening?“
hmmm, DBA’s life is tough afterall.
The DBA as usual run all the script he has on hand, only to find out the database is working fine.
About 70-80% of such incident I faced were becasue of application issue or a non-database issue. But it doesn’t stop the people from yelling “Summon the DBA…“
Anyways, a good DBA must be prepared for this kind of situation. He should get all his tools – monitoring script, performance stats scripts – ready to face this situation. Some uses nice fancy GUI tools, but others like me uses sqlplus. I usually have few useful sql scripts to check the v$session, v$session_longops excetra excetra. It saves lot of time and energy.
