Diego Costa's implosion this past week, leading to his first straight red card of 2015-16, was a rather metaphorical situation for the overall state of Chelsea.

The red card came amidst a defeat in the FA Cup that signaled the end of Chelsea's season, as the club has not chance at winning a single trophy by May.

For Costa, the card was the first straight red he received at Chelsea, but the Spanish international has been known for his reckless and often controversial play. In this instance, he put on his best Luis Suarez imitation and seemingly attempted to bite the neck of Gareth Barry of Everton.

But the moment, which was the new low for Costa, was the climax of what was a growing list of frustrations surrounding the player.

When Costa arrived at Chelsea last summer, he was coming off a season in Spain that saw him as one of the top scorers in the world. So great was his potential, that Spain did its utmost to sign him to the international side away from Brazil in time for the 2014 World Cup. While Costa surged to top form for Madrid, his work in Brazil was horrid.

His arrival at Chelsea however offset any concerns about his ability as the superstar went on to score 20 goals in the Premier League and 21 overall for the Blues in all competitions.

All told, it seemed like a strong purchase.

Disciplinary Issues

But 2015-16 has been a different story for the scorer. He has just eight goals in the Premier League and three assists to go along with 14 goals overall. At this point in time, his ability to match 20 goals is in great peril and his status at Chelsea is uncertain thanks to his attitude.

So who is the real Costa? The prolific goalscorer of seasons past or a man whose controversial antics make him more of a hindrance to his club?

In 2015-16, Costa has 11 yellow cards and one red in all competitions for Chelsea. No other player on his club has more yellow cards and one could make the argument that several of those cards could have been reds with different referees. That comes a year after he managed a 12 yellow cards for his club. Since 2012-13, the season when he first came to prominence, he has averaged around 11 yellow cards per season, certainly not a great figure by any standards.

So then why would any team want to keep him around? The goal scoring?

Goalscoring Highs and Lows

In his last four seasons, he has averaged 20 goals overall, buoyed by a 35-goal season for Atletico Madrid in 2013-14.

The numbers really get interesting however when one looks at how he actually did for Chelsea over the long haul. At the start of the 2014-15 season, he put up 18 goals in his first 15 games, including eight in the first four matches of the season for Chelsea.

But then he went into a horrid slump, producing just three goals in the final 12 matches; he even went seven games without a goal in that slump.

This season, Costa has gone in the inverse direction with his goal scoring, slumping early and getting hot late. Through 40 appearances, he has 15 goals, but 11 of those have come in the last 16 matches; in the other 24 games he has just four goals. These numbers include both club and country.

Underlying Statistics

Underlying statistics paint another interesting portrait of the striker's struggles.

This season, Costa is averaging fewer shots per game when compared with his best years for Atletico and Chelsea. While he is getting around 2.5 shots per game this year, he had 2.9 a season ago and 3.1 the year before. In 2014-15, he was scoring at a 26 percent conversation rate and a year earlier he converted 24.7 percent of the shots he took this year. His career average is around 20 percent.

This year he is only scoring at an 18 percent conversion rate.

Of course the career average is weighed down by earlier seasons when he was not quite as prolific. At 27-year-old, Costa is in the prime of a striker's career, which goes for at least another two seasons.

This all emphasizes two things. Costa, as a striker, relies heavily on his teammates to help create his chances. Chelsea underwent a horrid season which reveals why Costa's attempts were down across the board. In 2015-16, Chelsea has managed 14 shot attempts per game, down from 14.8 a season ago.

Secondly, his dip in conversion rate shows that he has had a slight bit of bad luck, particularly in the early going and that he is regressing back toward the mean and has the potential to score more goals.

Chelsea will likely be a far better club in 2016-17 and create far better opportunities than it has this season. That should help Costa's goalscoring increase back toward the 20 goals he is capable of scoring in the Premier League season after season. As it stands, he is the eighth best scorer in the league to this point. If he gets better support and a bit more luck, then he will be top three once again.

Despite his disciplinary record, Costa has been more beneficial to outcomes that he has as a hindrance. Chelsea should not sell him at any cost unless one of Neymar, Lionel Messi, Cristiano Ronaldo, Luis Suarez or Robert Lewandowski is coming through the door.

Of course at the end of the day this is a major cultural question that Chelsea must decide. Suarez was shipped out of Liverpool and his arrival at Barcelona was met with calls for a change in attitude. He has never looked back. 

Costa is a similar animal and the team might simply feel that there are enough goals to go around for this team to be successful and that a cultural issue like Costa is better off elsewhere.