5 Defining Moments in 2016-17 Chelsea Fans Might Forget About but Shouldn't

Chelsea are seemingly running away with the Premier League. They're eight points clear of second-place Manchester City and are going strong in the FA Cup, too, meaning manager Antonio Conte is on course to record a league and cup double in his first season at Stamford Bridge.

It's a far cry from where they were at the same stage of 2015-16, when the Blues faced the reality of missing out on European football altogether as they collapsed spectacularly in the defence of their Premier League crown.

Chelsea's position of strength now couldn't have been imagined as recently as the start of this season. As brilliant as they have been, Conte's men have had to negotiate some tough periods this term when their campaign was under threat.

From negotiating the frustrations of the transfer market to disappointing defeats, Chelsea have seen it all. Their path to the top hasn't been plain sailing.

So what are the most defining moments that have gotten them to where they are? Bleacher Report takes a closer look.

David Luiz's Transfer Back to the Club

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When Chelsea were getting knocked back by most of Europe's leading defenders last summer, who thought signing David Luiz would be the masterstroke that would help return the Blues to the top of the Premier League?

We'd put our sizable mortgages on there being nobody other than Luiz himself feeling confident he could make a return to Stamford Bridge work. We're not even sure Conte was convinced it would bear fruit.

The fact that Luiz arrived back at Chelsea on transfer deadline day last summer tells us he was a late choice for the Chelsea manager. Regardless of all the rumours that had circulated for much of the window, leaving it that late to sign a player doesn't put a lot of confidence in his ability.

Chelsea needed defensive reinforcements, and with the last day of the window, they had to go with what was available and not what they thought they needed. It meant Chelsea and Conte got Luiz back from Paris Saint-Germain.

Well, we all have egg on our faces now after ever doubting the move, as the Brazilian is a strong contender to be Chelsea's Player of the Year. Playing in the libero role of Conte's 3-4-3, he's been a revelation.

Signing him has changed Chelsea in ways we never thought possible. Luiz has rejuvenated the Blues' style of play, and they're much better for it. And it all came from a failure to sign another player deemed to be better.

The Humiliating 3-0 Defeat to Arsenal in September

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It was the game that sparked an overhaul, but despite all the benefits that came from Chelsea's 3-0 defeat at the hands of Arsenal in September 2016, it's a moment that still reminds us of the frailties that exist within the current Chelsea squad.

Sure, the Blues have lost just one league game since and went on a 13-game winning streak to take control of the title race, but it was a painful experience against the Gunners. Arsenal dominated them at the Emirates Stadium, and when we consider how Chelsea recently put Arsene Wenger's side to the sword so effortlessly, it frustrates all the more.

Losing the way they did revealed the ugly side of Chelsea. The game is a reminder that, for all their brilliance, issues still remain in the dressing room. As we saw in 2015-16, there is something lacking that means players can collectively down tools when they're faced with tough challenges. The character of old that has been associated with Chelsea isn't quite there, and Conte's on a mission to restore it.

Much has to be said for bouncing back the way they did. It was an indicator of how strong they can be when at full strength, but the loss shouldn't be forgotten.

Rumours of Antonio Conte Getting Sacked

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It wasn't long after that shocking Arsenal loss that rumours abounded that Conte was going to be sacked as Chelsea manager.

He was barely three months into the job of rebuilding the club, but when Paddy Power and other bookmakers stopped taking bets on his dismissal, the media went into a frenzy.

"All Bets Off" was the headline in the Sun, which reported that a flurry of bets on the afternoon of Oct. 13, 2016 had fuelled the rumours that Conte was going the same way as the other seven permanent managers who have worked under Roman Abramovich since 2003.

Chelsea were quick to deny the rumours, and Conte even laughed them off at his press conference that preceded a home match with Leicester City that week.

Chelsea had beaten Hull City 2-0 10 days before the sack rumours emerged. That was the start of the 13-game winning run that would transform the season and title race.

Where would the Blues be now if those rumours had any truth to them?

Losing to London Rivals West Ham United in the EFL Cup

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In the grand scheme of things, Chelsea being knocked out in the early rounds of the EFL Cup doesn't seem like a big deal. After all, the Blues are at the top of the Premier League and have bigger fish to fry in the FA Cup, having reached the quarter-finals, where they will face Manchester United.

But losing to West Ham was a massive disappointment. For a club that has prided itself on winning anything and everything in the past decade, Conte's side should've made a concerted effort to win their fourth League Cup since 2005.

Not only was it a good opportunity to get the club back to winning ways after the disappointment of 2015-16, but winning the competition also felt more realistic than it has ever been when we consider that Chelsea have no European commitments this season.

Jose Mourinho will compete in the EFL Cup final at Wembley this weekend. Despite their struggles at times this season, his Manchester United side are on the cusp of claiming another major trophy. Should they defeat Southampton, it'll mean the former Chelsea manager is gradually building a winning ethic at a club that has struggled since the retirement of Sir Alex Ferguson.

Losing to West Ham and going out of the competition when they did felt like a missed opportunity for Chelsea, not to mention that defeat came against a London rival on a night when crowd violence also marred the occasion.

Diego Costa's Flirtation with a Move to China

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Just when we thought Chelsea had negotiated stormy waters and were set to cruise to the Premier League championship, Diego Costa threw a spanner in the works.

It was Jan. 13 when horror struck: Costa was reportedly cashing in his chips to move to China.

The news was broken by John Percy of the Daily Telegraph and Matthew Smith of the Daily Mail simultaneously on the eve of a trip to Leicester City, with the consensus being that Costa had fallen out with a member of Chelsea's medical team and Conte.

On the back of that, rumours of a big-money move to the Chinese Super League surfaced, and it all seemed to be over for Costa and Chelsea. How could he and the club ever come back from this betrayal?

Well, Chelsea won 3-0 the following day at the King Power Stadium to reinforce their title credentials, with Costa left out of the matchday squad with an apparent back injury.

And as the dust has gradually settled, we're hearing now that the striker is expected to sign a new deal with the Blues.

Costa had been on a run of poor form that coincided with the rumours surrounding him, but he ended that by scoring against Wolverhampton Wanderers in the FA Cup. The hope now is that the bad news is behind him and the club.