Newcastle United, as ever, remain perhaps the most inconsistent team in the world. After a thrilling performance at home to West Bromwich Albion last time out, the Magpies utterly capitulated this evening.

After falling behind to Diego Costa's goal, an early setback, it seemed as if the visitors were not content at simply having the single goal deficit.

Rolando Aarons, playing out position to be fair to him, offered an awful square pass to Daryl Janmaat when Chelsea were looking to break, allowing Pedro to race through.

The World Cup winner then added another after Willian had notched. Some glaring lapses in concentration afforded the Blues three points today.

As bad as the away side were, Chelsea were clinical when pouncing upon their opponents mistakes, tearing the Toon apart with their robust midfield runners.

Willian in particular, impressed when dropping deeper into the engine room and dragging his team forward.

So, what did Chelsea's rout of Newcastle teach us? Well, here's FIVE things.

THE BAD SIDE OF SHELVEY

A lot has been made about Jonjo Shelvey ever since he joined the North East giants for £12m in January. While he's impressed at home with some of the fine passing we know he can produce, questions still remain about his application.

Too often today, when the going got tough, did the England international waste possession, giving it away in a sloppy fashion. It's the first time that side to his game has been on show since his move from Swansea City.

NO DEFENCE

Despite millions being lavished on the attacking department (which still isn't that great) on Tyneside, the sheer inability of their rearguard could really undermine their efforts to stay in the Premier League.

Ok, there are injuries dogging the club, but even when at full strength, it doesn't really look like a Premier League backline.

It's been painfully obvious that the club are in desperate need of defenders for about 18 months now. A left-back has been missing since before Davide Santon left.

It's unfortunate Rolando Aarons had to suffer through it today, but the club can't deny the warning signs.

WILLIAN CHELSEA'S BEST

The Brazilian has been Chelsea's best player all season, not befitting of a team who find themselves languishing in mid-table.

While most notably a winger, his penchant for dropping back into midfield and dragging the team forward is becoming one of the major trademarks of their play.

He's robust enough to move in to central areas and act as a catalyst for the likes of Eden Hazard and Pedro to run off of him. Not a typical Number 10, but certainly emerging as a hub of activity.

PEDRO NOT AS BAD AS FIRST THOUGHT

So much was made of Pedro's arrival from Barcelona, with the Spaniard boasting a hugely impressive trophy haul at both club and country level.

It's fair to see it hadn't clicked for him until today, though the World Cup winner proved just what a good player he can be. While he's not the typical La Masia graduate, he remains an incisive wide forward who can create danger.

Yes, things were offered on a plate to him today, but his goals were well taken finishes that required a cool head.

NEWCASTLE REALLY COULD GO DOWN

The influx of players in the transfer market had fans and pundits alike praising the club's work, suggesting they had enough to stay up.

However, they remain in a very precarious position. Slipping into the bottom three, the form of Sunderland will make for some very nervous remaining games on Tyneside.

Perhaps, other than Aston Villa and Norwich, you could argue the Toon Army are at the greatest risk of facing the drop.