Second, you still have not addressed my point of how bad defense leads to so many other bad things that I have listed in every post. Please address this. I will keep asking you until you do.
It's just a statement. You haven't quantified it so it's mostly meaningless. For instance, I have no doubt that pitchers will feel more comfortable with a slick-fielding SS. That doesn't say anything about how much it actually impacts their performance.
My whole point is that is can not be quantified with stats, because the effects are too complex. But here goes my attempt at it.
"SS is the most important defensive position on the field. It's importance can not be measured by any fielding stat, or any compilation of stats. Having a solid fielding SS results not just in less errors, or more plays made, it leads to less pitches being thrown by the pitchers,"
An error or a missed play means that the pitcher needs to pitch to at least one more batter, usually more. For every missed play or error, I think it is safe to assume that a pitcher will throw at least 10 more pitches. If a fielder gets to one less ball every other game, that means that a starting pitcher will throw an additional 150 pitches in a season, or another start and a half. Or to go another route, the pitcher throws 10 more pitches in that game, which means that he pitches one less inning than he should. This means extra work for the bullpen, plus it means you have your best pitcher out for one less inning. The extra work for your bullpen means that you will have less options throughout the season to use the right matchups, because guys are tired.
Like I said, it is very complex math to figure out exactly how many runs that means over the course of a year, but it clearly is significant.
"letting pitchers have confidence in allowing the batter to make contact"
This is not the same as "pitchers will feel more comfortable with a slick-fielding SS". It is not about their feelings, it is about how they approach hitters.
If they don't have faith in their defense, pitchers will try to strike everyone out. First, that makes them predictable, and thus easier to hit. Second, it adds heavily to their pitch count. This is much more than the 10 pitches because of a bad play. This is for every hitter. I would conservatively say that this approach adds at least 1 pitch per batter or around 20-25 pitches to a pitchers pitch count. So it has the same effect as a bad play, but at least twice as much.
"less AB's for the opposing lineup which means that the best hitters hit less often"
This is an really important one. This is exactly why walks are so important. Giving Albert Pujols one more at bat each game can be deadly. Preventing that can be the difference in games. Again, no way to know the actual #'s of runs this costs over the course of the season, but it is significant.
And here is one more I did not list. Turning a double play.
Think of how important double plays are in games. They are rally killers. The make it extremely difficult for teams to score in that inning. If a team does not get a double play, at best it continues the inning and leaves at least one man on base, at worse, there are no outs made and at least two runners are on base. In addition to all things I said above, this directly gives the other team a good scoring opportunity when there should be none or the end of the inning. Let's just say it happens once a week. That would mean 27 more chances for the other team to have a big inning throughout the year.
Bad defense leads to all these things, plus the direct runs that the player missing the play leads to. I am not going to give a number because there is no way to know what that number would be, but hopefully you can see that it is significant enough to make sure that you have a SS that can make all the plays he should. The one thing I will say is that all these side effects that you think are not significant, probably lead to more runs than the actual direct effect of not making the play.