Statistical Analysis: Has Petr Cech let his form dip for Chelsea this season?

Petr Cech has consistently proven that he is one of the best goal keepers in the Premier League and possibly in the World. Prior to getting his career threatening head injury he was arguably the best keeper in the league. Even in the aftermath, whilst having the odd shaky moment he was generally a very consistent performer for Chelsea. Has he though been below par this season?
Statistical comparison

	Clean sheets	Goals conceded per game	Defensive errors	Saves per goal	Saves per game	Avg. claim success
Cech	3	0.91	1	1.70	1.55	100%
Lloris	7	0.50	0	4.60	2.30	100%
Boruc	6	0.45	1	3.80	1.73	100%
Szczesny	3	0.91	1	2.70	2.45	95%
Howard	6	0.91	1	2.44	2.00	94%

These keepers are the top five keepers (although not listed in order above) according to Squawka’s performance score ranking. If we compare Petr Cech to the other keepers we can probably say that he is the weakest performer here. Cech makes less saves per games and concedes more goals per save than his rivals. In fact, he is some way ahead of Hugo Lloris and Artur Boruc in this regard, which is a concern for Chelsea. Cech isn’t making many saves, yet has still kept just three clean sheets.
Hugo Lloris is by far and away the best goal keeper here, closely followed by Boruc. Lloris has kept an impressive seven clean sheets, is making a lot of saves and is largely responsible for Spurs’ solid defensive record. Despite keeping seven clean sheets, he has been forced to make the second highest number of saves per game (after Wojciech Szczesny).
In terms of errors we can see that all of the keepers barring Lloris have made an ‘error.’ This describes an obvious error, rather than positional mistakes etc. that cannot really be quantified in the same way. For Petr Cech one can assume this was his howler that allowed West Brom to score their second goal during the last round of Premier League fixtures. That being said he’s had other moments. Against Manchester City he was caught out at the near post by Sergio Aguero too easily. Yes, it was a snap shot on his weaker foot, but Cech’s angles weren’t good enough and he was beaten very easily, when really he should have been able to parry the shot wide.
It’s worth noting that Cech is now 31 and will be 32 before the end of the campaign. He does of course have a number of years left in him but his current form has been a bit of a concern. This is especially poignant if we consider that Chelsea have arguably the best young goal keeper in the world out on loan at Atletico Madrid. Thibaut Courtois is just 21 years old but has firmly established himself as the number one keeper at Atletico, not only that but he’s kept five clean sheets this season and concedes a goal every 2.63 saves, a better rate than Cech, even if it is tough to compare different leagues.
Conclusion
Petr Cech has been a brilliant servant for Chelsea. His form over the years has been consistently good. Even when he suffered a dip after his head injury, he was still at a very high level. That being said, mistakes have crept into his game a bit over the last few years, becoming more frequent, rather than completely isolated incidents. His command of the box is still brilliant though, but there might be an argument for Chelsea to bring Courtois back next season to put pressure on Cech and eventually take over from the Czech keeper.
    culled from ThinkFootball