After Chelsea's title hopes took a severe blow with defeat to Sunderland, Matt Stanger ponders where it went wrong for the Blues. Jose Mourinho has much to answer for...
While other managers have been quick to speak about limitations, Brendan Rodgers and Roberto Martinez have pushed the boundaries to embarrass their peers...
* No-nonsense Tim Sherwood may do Spurs some good in the short term by simplifying things. By merely having a different approach to the last guy, Sherwood's appointment wasn't the most illogical choice in order to lift whatever was preventing their excellent and expensive collection of players from performing. And going on his first few league games, whatever he's doing (or perhaps isn't doing) seems to be working.
However, there's keeping things simple, and then there's blindly sticking to the traditional, English, meat and potatoes 4-4-2 when the opposition demands something just a little more...well, complicated. Even though this was not necessarily Arsenal's first-choice midfield, it still featured Jack Wilshere, Mikel Arteta and Tomas Rosicky, three men who, if nothing else, like to keep hold of the ball. To try and combat them with Mousa Dembele and a 19-year-old Nabil Bentaleb, making his full debut for the first team, was at best naive and at worst just stupid. If you keep things simple all the time, it might just look like you're not thinking about it.
* That said, Sherwood wasn't helped out by some calamitously bad performances by his players. The defending was often half a step up from slapstick (more on that shortly), Christian Eriksen was anonymous and Emmanuel Adebayor even more so. Sometimes it doesn't matter what tactics a manager chooses if his players are useless.
* Sherwood's instructions also seemed to extend to encouraging his players to test out Jack Wilshere's shinpads as much as possible in the first half, at least. Whether that was to actually try and injure the Arsenal man or just to test his patience/temper isn't clear, but while Wilshere isn't the most likeable character in the world, you could hardly have blamed him for getting a touch ratty with such rough-housing.
* Santi Cazorla's goal was of course superb, from the impressive Serge Gnabry's inch-perfect pass to the drilled low finish, but some fingers of blame should be pointed at Kyle Walker, who was desperately out of position, around five yards further up the pitch than a defender should have been at that point. Walker seemed to be positioning himself for a potential attack should someone else win the ball back, rather than trying to do so himself, which is the problem with having a right-back whose first instinct is to attack. In addition, for the second goal, while the main fault was obviously Danny Rose's (Spurs really, really need a proper left-back), Walker used his blistering pace to catch up Tomas Rosicky, but once there he couldn't tackle or even simply be strong enough to put the Czech off.
* Note to anyone irked, offended, ticked off or annoyed by Theo Walcott winding up the Spurs fans by reminding them of the score; this is one of the oldest and biggest rivalries in English football, his team was 2-0 up and he was presumably on the receiving end of some spicy language from the away section. Why wouldn't he do that? What on earth are you doing watching football if you think that's out of order? Incidentally, it was the daft grin on Walcott's face, plus the hilarious outrage from some of those Spurs fans, rather than the reminder of the scoreline that made it.
* Spurs applied for the maximum 9,000 allocation for their fans in this game, as visiting clubs are usually allowed 15% of the total capacity for cup ties. This was denied by Arsenal, with just 5,186 tickets provided on 'safety grounds', apparently. This of course being a fierce local rivalry that kicked off at 5.15 on a Saturday, giving even vaguely committed drinkers all day to fill their boots. A strong day all round for the football authorities.
* No doubt there will be plenty of wry grins from wry grinners after Sheffield United knocked out Aston Villa, given that Paul Lambert said he could do without the cup this week. Sure, laugh it up, but Lambert didn't exactly play a team of kids and blow a rasberry at the famous old trophy. He made four changes to the side that beat Sunderland last time out - one of those was because Nathan Baker injured himself in the warm-up, another giving a chance to young keeper Jed Steer, which seems sensible, and another was the introduction of Ciaran Clark, who has made 16 appearances this season.
By way of comparison, Steve Bruce made nine changes to the Hull side that beat Middlesbrough, so who's 'disrespecting' the cup? Clearly, neither manager sees the competition as a priority, and Lambert's mistake was to say so out loud then pick a group of players that really should have been good enough to beat the side 18th in League One and who lost to Walsall on New Year's Day. There are reasons to criticise Lambert, not least their style of Villa's play and where some of his summer spending went, but how seriously he takes the FA Cup is not one of them.
* There aren't many areas of their squad that you might describe as 'deficient', but one wonders if Manchester City might consider investing in a goalkeeper this month. Joe Hart has been better since his return to the first team, although he did get away with a frightful gaffe against Swansea on Wednesday, waving at a cross that Swansea couldn't take advantage of. However, Costel Pantilimon displayed once again that he's not exactly a reliable back-up by fumbling the ball into Scott Dann's path for Blackburn's equaliser. There's even some talk that Pantilimon, whose contract expires in the summer, might want to leave if he isn't a fixture in the City side. The Romanian clearly has a higher opinion of his abilities than most, but if he does want to leave anyway, now might be the time for Pellegrini to invest in a little goalkeeping depth.
Speaking of goalkeeping, Paul Robinson made his first appearance since November 2012, missing over a year of football through a combination of back surgery and a terrifying-sounding blood clot on his lung that, but for the quick thinking of Blackburn's club doctor, might well have killed him. Still, despite his tough time, it was notable that all the old Robinson problems were there in his performance against City, in particular the curious hop/trigger movement that made him a bit of a liability against long-range shots, even in his England days. Most goalkeepers have such a tick to get their feet moving, but Robinson has always managed to time his so he is descending from the jump at just the wrong time, meaning he has less time to push off and dive to make his saves. At 34, it's unlikely that will ever change.
* Dedryck Boyata generally doesn't get much first-team football these days. Given he's behind Pablo Zabaleta and Micah Richards in the right-back pecking order, that's hardly surprising, but it probably says a lot about how highly Pellegrini rates him that the very left-sided Gael Clichy has usually been preferred in his position when both of those two are unavailable, and that he was only trusted with a start at home to Crystal Palace - a game in which he was the first player hooked (after 55 minutes) when things weren't going their way. Therefore, at the start of the transfer window, with plenty of teams who might be able to offer him regular football looking around for new blood, this was perhaps his chance to 'put himself in the shop window', or at least remind anyone watching that he is still alive. Getting sent off for a pair of relatively brainless bookings probably wasn't the best way of doing that.
* While the extra game is not ideal for Manuel Pellegrini's side (in a busy-enough period even without it), one bright side for City's players might be that at least they won't now be schlepping all the way to Dubai in a couple of weeks. City were pencilled in to help open the Hazza bin Zayed Stadium in a friendly against Al Ain on January 14, but as the replay will probably now take place on that date, City now have a solid excuse for giving it a miss. Unless it's rescheduled, of course...
* The 'faint praise of the day' award goes to Steve McManaman, who proclaimed that Blackburn had "covered themselves in a lot of credit". Stop it Macca, you're making them blush.
* The glory of the cup is all very well, but Sean Dyche might have been well-advised to take their game against Southampton a little less seriously. For a Championship team to lose at St Mary's is nothing to be particularly ashamed of, but Dyche put out virtually his first-choice team, barring a couple who had knocks and weren't risked. "I want us to go there as strong as we can and we will not be resting people, that's for sure," said Dyche before the game, which is admirable, but Burnley's squad is very thin, and while they're currently doing superbly in the league (they're in the automatic promotion places and have been for much of the season), they've been relatively lucky with injuries.
Ten of their squad have played 18 league games or more, but the law of averages and indeed basic knowledge of physiotheraphy says that level of fitness won't last. In particular, if anything happens to either Danny Ings or Sam Vokes (responsible for 25 of their 36 league goals), they're bang in trouble. A cup run would be lovely, but Burnley obviously have more chance of getting promoted than doing anything of significance in the cup, so this was perhaps a good opportunity to give his presumably tired first-team players a rest.
* One of the more topsy-turvy games of the day came at the DW Stadium, where Wigan went 2-0 up, only for MK Dons to peg them back with two goals in a minute, then Callum McManaman made it 3-2 before six minutes from time, Patrick Bamford earned the draw for the Dons. That was Bamford's 17th goal of the season, and his final one for the Dons, as the Chelsea youngster is now off to try his hand at a slightly higher level, with Derby. Steve McClaren's side have been on a fantastic run of late, but are showing signs of slightly running out of steam. Reinforcements like Bamford could well keep that run going for a little while yet.
* "We're sh*t and we're sick of it," was the chant from Leeds fans after their shambolic defeat to Rochdale, a defeat that prompted one of football's lesser-seen/heard events - the managerial apology. Brian McDermott said sorry after the 2-0 loss, and claimed it was his 'worst moment in football' - and this from a man who has lost a play-off final. Leeds have been on a quietly dreadful run recently, slipping out of the top six in the Championship, their troubling reliance on a couple of players proving problematic. Ross McCormack has scored a little under half of their league goals this term, and their midfield lacks creativity when youngster Alex Mowatt doesn't play, so when one/both are absent/quiet, they don't have a hugely inspiring side. To be so reliant on two players is bad, but when one of them is 18 (born in 1995 - commence feeling ancient), well, that's just embarrassing.
* Of course Ole Gunnar Solskjaer's first win as Cardiff manager was gained from behind and secured through late and vital goals by two substitutes. Of course it was.
* Theory: Macclesfield's draw with Sheffield Wednesday wasn't inspired by this, ahem, 'Churchillian' speech apparently put up in their dressing room, but by the anger their players presumably felt after seeing the shambolic grammar on display.
Nick Miller - follow him on Twitter