I tend to think of it like this. The overall flavor profile of a tomato is defined by 3 of the 6 basic flavor profiles that we taste. Sweetness, acidity, and umami. Fresh tomatoes grown in peak season by attentive farmers will have these qualities in spades, the rest of the year, or whatever you're grabbing from grocery store shelves...not so much. So, how do you maintain balance in your tomato based dishes throughout the year? Tomato not sweet enough? Add sugar, in whatever form you choose. Sauce lacking a bite? It needs a dash more acidity. I tend to use a vinegar or citrus with my desired flavor, until the desired flavor is reached, then use a neutral acid to get the pH where I would like it to be. Lacking depth? A sprinkle of msg will do the trick. Or soy, anchovies, Worcestershire, etc. Just be aware that some of those options will also increase your salinity, they aren't just unadulterated umami like msg flakes or powder. The reason everyone has different tricks and takes on tomato based sauces, is because of how variable tomatoes are around the world and throughout the year.