Penetration testers versus traditional testers

Really in the first I have faced some confusion about my actual role in my career.
At the first I have conduct very systematic testing activities followed & monitored by processes.
By the time I have faced some cases which enforcing me to do some penetration testing which from my own perspective conducted by some non sequential scenarios .
So , I get used in my working characterizes to do that role,
At the beginning , I interested to walking through the application & determine what the testing were be fitted to that application.
Actually , after my smallest experience I decide to use the both techniques in my testing activities .
The first one is Following all processes till making sure from all basic requirement .
The second was to do some penetration testing which make me able to do some activities :
1-present some enhancement for the Client requirement,
2-detect all available vulnerabilities which maybe not detected by the traditional techniques.
3-make some rapid application development.
4-becoming have some creditability with the developer side.
Certainly I decide to use that way of testing which I feel that very fitted to my characterizes.
But , I can’t tell other people about what I do & the QCs still answered why I becoming have some creditability with the developers & PM.
The main reason was I have Combined between two techniques of testing Agile testing & CMMI traditional process.