I consider myself pretty decent at the game. Probably not good enough to get Elite in WL, but somewhere thereabouts. Haven't actually tried it yet as I've played mostly Clubs and Seasons this year, but am thinking about giving it a go. Anyway, the point is I'm good enough to win most of my games, but I still feel whinging about bad gameplay or broken game mechanics or whatever is totally legitimate. My views on the issue, after thinking about it rationally for a few days, is as follows:
The game is skill-based enough that it will reward good players with wins even when the flaws in the game go heavily in favour of the opponent, because they're able to overcome the extra challenge of playing "against the mechanics" or even knowing exactly how to exploit broken mechanics in their favour. This doesn't mean that there is momentum or scripting that determines the outcome of the game, necessarily. I think it's like a coin throw, basically. In a long sequence of throws the results should even out over time, but take a small segment of the sequence and there might be a vast majority of either heads or tails. In the same way, a long run of games will have a fairly even spread of the bad mechanics working for and against you, but there will still be games where the FIFA shite will be working heavily in favour of one of the teams, which is how I think the idea of momentum pops up. A rebound can lock itself straight to the nearest attacker despite the keeper initially deflecting it in a completely different direction. There are videos on an earlier page in this thread. Who it falls to might be a random outcome every time, but one player can score several goals because of this and the other can get zero despite having similar rebounds from the keeper. An outcome being random doesn't mean both players will benefit or get hurt by them the same amount in every game. An example is this video of one of my games from FIFA 16:
Yes, I give him far too much time in the box for the first goal. I also allow him a free pop from distance on the second, preferring to block the run from the striker instead. Then his third goal is just a complete brain aneurysm from my goalkeeper to complete it all. Not great defending on my part for any of the goals, but when he fails to produce good finishes, the game still helps him get the ball over the line for whatever reason. Meanwhile, for my three goals he also defends very poorly, but I actually manage to get the ball into the net on the first attempt each time, without requiring any extra assistance.
There's also the case of mechanics working against you being so much more noticable than the mechanics working for you, especially as you get closer to the line between luck and skill. Say you play a pass to your winger, cut in and score. You might think it's a great pass and a sublime piece of skill, which to be fair it also probably is, but if there's sluggishness in the gameplay or input delay or whatever, that might have been the difference between the defender intercepting the pass or blocking the skill move and you scoring the goal. Because the defender has to read and react to the moves of the attacker, the defender is at a greater disadvantage when the game feels more sluggish than usual, and it's extremely easy to notice when a player feels unresponsive compared to his normal self. We've probably all conceded goals because of it, but put yourself in the attackers shoes. They will think it was all because of how well they executed the moves in that particular run of play. It's a fine margin, but in tight games between players of fairly similar skill it can enough to push the advantage from the defender to the attacker, or even vice versa.
There are also far too many seemingly jammy goals where no controller input will prevent the goal. A shot from an unfavourable position getting spilled right into the path of an incoming attacker, for example. The defending team has forced a fairly poor shot from distance instead of allowing the attacker to work the ball into a more dangerous area and because the bad rebound scripts the game still gives the attacking player a free shot at an open goal. I've watched extremely good players play each other and there's still an unreasonable amount of shite goals where the ball bounces off the post, the keeper or the defender and lands straight in the path of an incoming attacker. Sometimes it even hits a defending player and bounces in, and because the defender is locked in an animation or does some other idiotic move automatically, the player controlling him can't stop it from happening. In a neck and neck game where one goal could be the difference, that's a case of bad mechanics (which the rebound player lock thing definitely is) directly influencing the outcome.
Automatic actions from players are a huge problem because they remove the skill aspect. If a player makes a clearance without controller input, which sometimes happens, especially in extremely hectic situations in the penalty area, the game is giving an advantage to one of the players depending on the quality of the clearance. It could prevent the defending player from conceding if he wasn't going to react to it, meaning the ball would have stayed in the danger zone, or a poor clearance could give possession back to the attacking team if the defending player has the ability to get control of the ball and safely play it out if the game doesn't override the controls to make the clearance. Unselected players barging in and getting headers or shots at goal from corners are another issue where the game can potentially literally score a goal with no effort from the player taking the corner, apart from having to get the ball somewhere within the box. Again, that one goal could be enough to win the game.
All in all, these are some of the reasons why it's perfectly legitimate to complain about FIFA being a poor game in some respects. The best player doesn't always win in football, FIFA or any other sport or E-sport, but compared to the biggest E-sports in the world, FIFA has massively unpredictable gameplay in far too many aspects of the game, and luck or other things not related to player skill directly influence the outcome of the games far too often. This is poor game design on EA's part regardless of who gets the rub of the green in any given situation, and it will have to be fixed for FIFA to become a serious contender to other games on the competitive scene. Entire tournaments
can get decided because of a bad script within the game rather than player skill, and that shouldn't be acceptable to anyone, whether they're playing a couch tournament with their mates or a pro tournament with cash prizes at the end.