Chelsea lined up in their usual 4-3-3, with three direct substitutions from their preferred XI. John Terry, Frank Lampard, and Nicolas Anelka were all out, were replaced by Branislav Ivanovic, Ramires, and Salomon Kalou respectively. Blackpool more or less matched Chelsea's shape, fielding an inverted version of the Blues central midfield triangle for the first half, with two strikers sitting fairly high up on the pitch and Alex Baptiste acting as a sweeper/defensive midfielder.It's slightly surprising that Blackpool's advanced wingers failed to do much. Chelsea's fullbacks pressed forward throughout the match, and as a result there was plenty of space to operate in down the flanks - it just wasn't taken. Meanwhile, Chelsea found the left side wide open. Blackpool right-back Neal Eardley was shadowing Malouda far too closely, and would regularly either follow the forward's runs towards the middle of the pitch or bomb upfield, leaving nobody to contest Ashley Cole on the entire flank. David Vaughan found himself shackled by Ramires, and in response drifted to the left, giving the Blues even more opportunity to overload that side.
Blackpool's strikers should have caused Chelsea more problems than they actually did, and as best I can tell it was simply poor passing that did them in. Jon Obi Mikel, who had another excellent game as a holding midfielder, joined in with Michael Essien and Ramires in pressing the midfield very hard, and the result was Blackpool looking disjointed whenever they were in possession. Mikel found himself high up the pitch far more often that he's used to, and he was obviously uncomfortable so close to goal. Ramires, who covered for Mikel when he made his strange incursion upfield, was fairly effective on the ball, and he sprayed a couple of excellent passes out to Paulo Ferreira on the right - typically, the Portuguese fullback wasted them both.
Chelsea dominated the first half by overrunning the right while harassing the visiting midfield into making mistakes. Blackpool's forwards were starved of service and couldn't get into the game, and they seemed loathe to get back and defend, always looking for the quick counter-attack. Chelsea going 1-0 up inside two minutes can't have helped Ian Holloway's mildly defensive game plan, and at times it looked like Blackpool were caught playing a split team - three strikers totally isolated from the seven midfielders.
The second half saw some significant re-juggling on the part of Blackpool. Eardley was withdrawn and replaced with Gary Taylor-Fletcher, an attack-minded midfielder, with Blackpool essentially playing a three-man defence as a result. Vaughan dropped to cover right-back whenever it was necessary and Baptiste was still playing fairly defensively, freeing up Taylor-Fletcher to push forward. Having another body in midfield gave the central players an outlet and helped Blackpool achieve more possession, and perhaps more importantly gave Ashley Cole some defensive duties to think about. Cole still managed some dangerous runs down the flank, but unlike in the first half they came at a defensive cost.
Figure 2: Chelsea (blue) vs. Blackpool (red), second half.
Blackpool's renaissance would not have been possible without Chelsea easing up. It's tempting to pin everything down to tactics, but the Tangerines looked much sharper after the break, and Chelsea were sloppy. It would have been no great surprise had Blackpool netted a consolation, and such a goal probably would have come down the right. Ferreira was sloppy all day, and Alex had some wobbly moments too. When the Blues finally righted themselves at about the hour mark, the visitors stopped looking so threatening - but the hole that Ashley Cole was exploiting during the first half was no longer so easy and Chelsea found it harder to generate chances as a result. It wasn't much harder, though and Chelsea really should have scored a few goals in the second half. At one point Blackpool were playing what appeared to be a 3-3-4 with a very high defensive line in trying to chase the game - not the most sturdy of shapes.
Blackpool didn't get beaten because of the tactics they played. They were beaten because Chelsea are a world-class side, and Blackpool, frankly, are nowhere close. There was no answer to the Ramires/Essien/Mikel triangle, nor to the movement of Drogba or Malouda. Not many teams still throw themselves forwards when down 4-0 at Stamford Bridge, but the visitors made a good go of it and probably deserved a goal for their troubles.