If your pension pays you $4000/mo as a benefit in retirement you would need to have $1,000,000 in the bank paying 4.8% to create the same income.

If you had $1,000,000 in a 401k or an IRA you would use utmost caution and due diligence to make sure the money was protected and working for you.  Often times, people with a $1,000,000 defined benefit pension don't use the same vigilance. 

Money contributed to a defined benefit pension is no different than money that is contributed to a 401k except in its distribution options.  We see far more mistakes in this arena than companies that only offer 401k plans.