Your skill will accomplish
what the force of many cannot
Let me guess ... and it's the same (Oracle) DBA who is helping tune your DB2 system. Different RDBMS, different magnitude of hardware ... same approach? If I were talking to the DBA, I would suggest asking IBM for help in tuning the migration. If I were the DBA, I would have tried to get that tuning in before plunking down the money. However, as neither case applies, the best you likely could do is suggest to the DBA that s/he talks to IBM, and suggest it in such a way that it sounds like the DBA's idea.