The Drastic Score Disparities

A majority of games I experience have near or greater than a 2 to 1 score disparity during a victory, or a 1 to 2 score disparity during a defeat. Score disparities are supposed to reflect the degree to which one team is better skilled and/or coordinated than the other team. Therefore, these scores could be considered to be a reflection of bad matchmaking, where much better players are teeing off against relatively poor players. Theoretically, the player ranking is correct in time after much ranked play, but I've seen these score disparities throughout the entire season. Ranked matchmaking isn't working as intended if score disparities are massive the majority of the time throughout the season.

However, I am of the opinion that the score disparities result for the game being snowbally, making the game less competitive past the first few bouts of success or failure. After the first few engages, if one team won the majority of them, they win the game decisively and the game stops being competitive. So, which is it? Are the teams unevenly matched the majority of the time, or is the game so snowbally that Riot needs to adjust the balancing so that games are more competitive again throughout the entire match like they were in prior seasons?