The failure to replace Robert Sánchez remains a mystery but the new-look front three should buy time for the new manager’s principles to bed in After a weekend on which pretty much every potential challenger to Arsenal had demonstrated their flaws , there was a sense, perhaps even a need, for Chelsea to emerge as a serious contender – if only to prevent the title race becoming a procession. And while they were far from flawless, there were at least some indications that they could mount some ki…