I don’t need to tell you this, but being a Mets’ fan is about being disappointed, frustrated and angry. It shouldn’t have to mean being betrayed.

After the disappointment of the Omar Minaya Era, which was highlighted by bad contracts – but at least he was signing people – the Mets were promised a new day with the hiring of Sandy Alderson as general manager.

Alderson vowed things would be different, and to be fair, they have been as worse is different.

“Be patient,’’ Alderson said, telling us it takes time to scuttle a team and rebuild with youth. Three years into the Alderson regime and the Mets still don’t have a bullpen, don’t have a major league outfield, the back end of their rotation is patchwork and there’s little depth.

Remember, Alderson was brought here – at the suggestion of commissioner Bud Selig – to get the Mets’ financial house in order. To that degree, he’s done well, shedding the Mets of the contracts of Oliver Perez, Luis Castillo, Francisco Rodriguez and Carlos Beltran.

Alderson got prospect Zack Wheeler for Beltran, but little else other than a fresh feeling for the removal of Perez and the others. After this season, he will be done with the contracts of Johan Santana and Jason Bay, the two biggest contracts given out in the Minaya Era. But, make no mistake, they were done so with the blessings of the Wilpon ownership.

To date, none of Alderson’s draft picks are producing on the major league level. Few of his trade acquisitions outside of John Buck have contributed, and the Mets remain the mess that prompted the management changes in the first place.

Only, the Mets are losing with a lesser payroll. Is that really progress?

If you’re a Mets’ fan this morning, you have to feel betrayed by what you saw the first month of the season, especially with what has happened the last two games. You feel betrayed because you bought into Alderson’s promises of better times to come and the spending during the winter of 2014.

Last night might have been the worst loss of the season.

After the Mets received eight scoreless innings from journeyman pitcher Jeremy Hefner – penciled in as a Triple-A starter going into spring training – their bullpen again collapsed. That’s three blown saves in two games.

It is easy to blame last night on third base umpire Tim McClelland’s blown call, but that’s only part of the reason why they lost.

They lost because their offense continues to be pathetic. While the onus has fallen on Ike Davis’ woes, he’s not the only one. The Mets have only one hit in their last 21 at-bats with runners in scoring position. The offense is dormant, and a lot of that stems from the fact they have no outfield.

Building a team is acquiring depth, but Anthony Recker had three bad plays in the ninth inning that led to the unraveling. Recker took accountability last night, saying he should have caught the pitch that turned into a passed ball; should not have made the throw to third, which because necessary because of the passed ball; and should have blocked Brandon Lyon‘s wild pitch.

Recker was stand-up about his performance, but he’s a Double-At catcher performing in the major leagues. He’s here because the Mets did such a poor job of building their bench.

And, why was Lyons in the game to begin with?

Bobby Parnell is the closer and should have gotten the ball at the start of the ninth. That was the formula, so why did manager Terry Collins deviate?

He said he didn’t want to burn out Parnell. Damn it, what are you saving him for, the World Series?

If he’s the closer, then he needs to go two or three games in a row. That he threw two innings the night before is avoiding the issue. Either Collins has faith in Parnell or he doesn’t. Parnell should have gotten the ball.

Even so, the Mets made a number of bad plays in the ninth inning, and missed several opportunities to lengthen their lead. Only, they didn’t execute, and much of that is because Collins doesn’t have the right pieces, and that falls on management. Why do you think the Mets didn’t post their line-up until moments before first pitch? It is because Collins didn’t know what pieces he’s have and if they’d fit.

Collins couldn’t rest David Wright, who has a stiff neck. Collins has to wait until batting practice to even see if Wright could play. He also had to figure out where Ike Davis would do the least amount of damage. Davis is batting seventh today, quite simply, because he has little other options on this level.

It is Alderson’s responsibility to give him those options. It is Alderson’s responsibility now that streamlining the budget has been addressed, of putting a representative team on the field.

So far, he hasn’t.