Veterans From Earth's Past

In the year 2408 after the Klingon and Gorn invade Cestus III a Starfleet Committee chaired by Admiral Jorel Quinn passed motion to explore other options and possibilities in order to build up the Federation with commanders and ships. "We need to promote exceptional officers quickly. We need our captains leading away teams. Starfleet needs to look at our whole command structure and do what works now, not what worked 30 years ago."

A Starfleet diplomat was sent back to the late 2260's to speak with Starfleet in order to round up several possible exceptional commander candidates and as many star ships as they could refurbish from the decommissioned roster.

The chosen captains were given ships that were pre programmed with precise calculations in order to  carry out the light-speed breakaway factor to artificially-created time warp in order to time travel back to the 2408.

Once the initial five captain were sent, Starfleet would keep their eye out for any such qualified command personnel to join the fleet and to help fight the war in the future.

You may be that commander!