How much are you prepared to forgive a reaaly bad run?

Find it interesting that both George B and myself have put up selections today in the comps that both ran abysmally lto, GBs pick Kode Secret btn 21 lengths lto and my pick Merisi Diamond btn 34 lengths lto, obviously we both think there may be excuses for their last runs and both have form to win their races on backform.
   GB has explained his reasoning, mine MD is trained by Joanna Morgan who has very few runners in recent years just 4 horses running in past 3 seasons. This horse has won 4 races with 2 2nds for her, 2 over C/D and 2 at the Curragh, 3 wins have come in Sept/Oct all on soft/heavy ground, inc this race last year from 3lbs higher. All good reasons imo to think has a good chance today, but i thought that lto as well. To me it's last run clearly wasn't it's true form as won race last season in a 2 second faster time than Earls did when winning in Sept, both on soft, yes i know times need to be on same day to be really relevent but still.
   Would you forgive its last run when regular rider Whelan said he thought horse "didn't feel right 1f out"? Has found support from last nights 14/1 into 13/2 with books this AM and 22-12 on here steadily.