Percent chance to win after taking a pre 15 and pre 20 minute Inhibitor

We all know the percent chance to win games after taking first inhib is supposed to be abount 90-92%. Now that statistic is just general and in most situations the team ends because they are drastically ahead and the first inhib had nothing to do with that win. So when, lets say top lane, is trading 1 for 1 but is a ranged champ and manages to get an inhib fairly quickly, around 15 minutes, does that actually decrease the chance to win the game. Getting an inhib funnels increased gold and exp to the enemy and if your team is not actually ahead, it would be detrimental to take inhib then. This is why I would like to know whether the % chance to win is above 50% or not figuring a gold difference to be within $2k at time of taking inhib.