I believe these people are just like me when I became a DBA. You never have seen a 3000 line SP, then you are asked to look into it.
The first key I received was from a fellow developer/DBA. He showed me how he highlighted a couple of lines of the SP, and just ran that part. At that point in time, I never 'knew' that I could debug a SP that way.
That event opened my mind to the possibility there were other ways to debug T-SQL code.
I then 'sought out' more ways to performance tune T-SQL, which lead me to SQLServerCentral.com, free books Red-Gate sponsored, PASS Summit, etc. etc. etc.
Thanks SQL Server community,
Thomas LeBlanc, MCITP DBA 2005, 2008 & MCDBA 2000