Who is Manchester United's most indispensable player right now?

You know how the rhetorical question 'Is the glass half-empty or half-full?' often is used as a simple litmus test to determine whether somebody is an optimist or a pessimist? When it comes to sports... I'm the type of the person who will tell you that the half-empty glass is dangerously close to reaching a level of emptiness and due to that soon-to-be emptiness, one will need to go on exhausting search for more water and due to that exhausting search, perspiration will occur and due to that perspiration, fainting may occur because of a dangerous lowering of blood pressure and due to that possible fainting, further stress is caused and this vicious cycle continues until you pass out, go into a coma, and ultimately die (*).

(*) For our U.K. readers, I hope this lovely paragraph greets you warmly this morning!

What is the point of this? I found myself pessimistically wondering recently which Manchester United player is currently most indispensable for our final four matches. Which player, if we were unexpectedly to lose him (**), would threaten our quest for title number 20 the most? Here is a list of players for this morbid possibility and discussion:

(**) Remember, the glass is half-empty!

* Wayne Rooney: The obvious player to think of is our talisman. Since his return to world-class form during last season's run-in, it could be argued that United became too reliant on Rooney. His combativeness and willingness to track back and defend frees up our passing central-midfielders while his creativity between the lines creates chances both for himself and others. As of late though, his touch has failed him somewhat and his all-around influence has been waning. However, he's still bagging goals -- and lots of them.

* Antonio Valencia: Our most incisive attacker since the new year has been the Ecuadorian right-winger. At times, he's simply been unplayable as he's continually abused whatever left-back the fixture list has thrown in his way. Valencia hugs the touchline to receive, stretches the opposition's defense, and he creates an endless supply of chances when he gets by his marker to cross from the byline.

* Paul Scholes: Since the maestro returned from a premature retirement in January, United have taken a possible 34 out of 36 points in the matches that he's featured in. The lone league defeat occurred during the only match he was rested for. The 37-year-old is pulling the strings from the center of the park and his arrowed and incisive long-diagonal balls have been hugely important in supplying Valencia near the touchline.

* Michael Carrick: The under-appreciated midfielder has started in every league game since the Swansea City fixture in November. He's been the stalwart in midfield since then as he's brought structure due to his tactical intelligence and he's brought calmness due to his metronomic distribution. He's also benefited by having Scholes to ping the ball around with -- but Scholesy has undoubtedly benefited as well by having Carrick partnering him in the middle.

* Jonny Evans: You've heard this a lot lately if you're a regular TBB reader, but it bears repeating -- Evans has been United's standout defender this season. Admit it, you crawled into a ball and started crying when our steely Serbian captain was broken in Switzerland. Okay, maybe that was just me. But I'm sure many of you thought that our chances of being champions again had been drastically diminished. Evans has been a rock in the back and he's even expressed himself in the attacking half of the pitch. He certainly deserves consideration for the Prem's best XI this season.

* Rio Ferdinand: It's been a mostly healthy run-in (***) for Rio and despite losing a bit of pace, he's adjusted well and kept his reputation as one of the league's premier central-defenders. His ability to read the game is superb and he's formed a tremendous partnership with Evans. Rio has provided cover for Evans when he steps out of the back and he's done the same for Patrice Evra when the left-back gets caught out too high. His ability on the ball has suited United's recent patient passing game as well. Also, there's the leadership he's undoubtedly providing.

(***) *Knocks on wood*

* David de Gea: Since his brilliant performance at Stamford Bridge, it would be impossible to ask anymore of a goalkeeper. The youngster certainly took some time to adapt during his debut season in England -- although I'll continually state that he was never as poor as most claimed he was -- but he's been simply brilliant for the past few months. He's shown tremendous improvement in commanding his box and his shot-stopping has been world-class. If he were to go down, we'd be left with the unproven Ben Amos.

Who is the most indispensable player right now when one considers roles, form, and possible replacements? Be sure to vote in our poll and also to share your thoughts in the comments section if it fancies you.