Clubs set out the season with different objectives. While one team may try to avoid relegation, another may want to win the league. But if both of those objectives are met by the respective clubs then it's a success for both.
For this reason I personally believe we could have a better season, because of our original aims. We set out for a CL spot and are still competing for that.
You set out to win/compete for the league. You did. United fans couldn't hold in their excitement when the signings of Pogba and Zlatan were announced in their triple figure million Black Friday esque shopping spree. And you got Mourinho too, the quick fix, instant success, always wins the league in the second season manager.
On top of that you had a good start to the season so there was double optimism. Halfway through however things started to falter, and you had to re-evaluate your aims, convincing yourselves that after the debacle of LvG a CL spot always should have been the objective and it was silly to think you could win the league straight away.
Yes you've won a League Cup and may even add a Europa league to that too. But at the end of the day had I told you (if this happens by the way) you'll end up 6th with a League cup and Europa League you'd of been a bit surprised considering the money spent and manager brought in. Although maybe you could of been convinced to accept it because of the Europa league. I don't know you tell me
However, if you told me we'd be knocked out of all the cups but end up 4th. I'd be happy. (Cups would have been a bonus but hey, 4th was always the aim).
Clubs set out the season with different objectives yes, and as you've pointed out, those objectives can change. With no European football, Liverpool's objective was top 4, and in all likelihood, a cup. Then you found yourselves 2nd and looking like the only team that could catch Chelsea, and the objective, at least from most fans, seemed to have shifted to a title challenge. Within a month you found yourselves out of the title race, and out of both cups, and suddenly it was back to "if you'd told me at the start of the season..." giving yourselves a big pat on the back because you'd managed to finally a win a league game in 2017 a month and a half into the year.
United fans were disappointed when the expected league challenge evaporated at the start of the season, but the fact we're now 22 games unbeaten in the league, have won a cup already, have a chance of winning another, are still in contention for the top 4 after beating the champions' elect very comfortably, and are, in the minds of many, playing much better than we were under our previous two managers, is something to cheer about.
This "if I'd told you at the start of the season..." bargaining is just pure nonsense, that unsurprisingly is coming largely from Liverpool fans as they try to convince themselves that yet another trophyless season is a "success" because they
may finish above United in the league. Besides, if we're going to to play that game, I think most United fans would have accepted two cups and Champions League qualification as a pretty successful season, with the aim remaining to challenge for/win the league next season.
I also don't get this satisfaction with winning nothing and finishing 4th. You've won one trophy in the last 10 years, and as I pointed out to redman, have only looked like qualifying for the Champions League in the last 8 when you've been able to play without European distraction. People have been critical of Wenger for years because he's been happy with winning nothing and finishing 4th, with each and every Champions League campaign being just as lacklustre and disappointing as the one before, and now the fans want his head. You qualified for the Champions League for the 2014/15 season, then gave up trying in the Champions League to...err...try and qualify for the Champions League. What's the point? Where's the endgame here?
There's no point being in the competition if you can't give it your full effort because you need to focus elsewhere just to qualify for it again. Top players don't care about being in the Champions League, they care about money and winning it. If you've got a squad that's used to fighting on multiple fronts, then you've got a squad that with the right improvements, could challenge for both the league title and the Champions League. United currently have such a squad, whereas Liverpool seem to be still stuck in this "if you'd told me at the start of the season..." mode that makes excuses for failure.
Last season it was "if you'd told me at the start of the season that we'd have made two cup finals..." as an excuse for finishing 8th. This season it's "if you'd told me we'd be in with a shout of 4th with a 5 games left..." as an excuse for bombing out of the title race and both cups.