Sam Allardyce and Everton did it again on Saturday. The manager’s second match against a big club was another hard-fought draw — a valuable point in the Toffees’ race to seventh place.

The popular narrative emerging from this match was that Big Sam had worked his magic again, throwing 10 men behind the ball and getting his team to defend hard for 90 minutes. That’s not entirely untrue, but it ignores the opening 15 minutes of the match, when Allardyce tried to do something a little more aggressive, and Chelsea nearly made him pay for it.

Recall Everton’s starting lineup from the match.

The changes in individual personnel were the first thing to catch most people’s attention (myself included), with Phil Jagielka and Michael Keane finally drawing back into the starting XI, and Tom Davies replacing the ill Wayne Rooney.

The most interesting thing, however, wasn’t the personnel, but rather its usage.

Sam Allardyce inverted the central midfield triangle, leaving Morgan Schneiderlin alone in a deep-lying role, while pushing Idrissa Gueye up into a more advanced role alongside Tom Davies.

Neither Gueye nor Davies were playing as a traditional No. 10, but both were clearly tasked to play as something closer to a box-to-box midfielder — and with a clear purpose in mind.

To best understand Big Sam’s goal, you need to understand the Chelsea setup as well. Take a look at Antonio Conte’s starting XI.

Conte has continued to use his 5-2-3 this season for...reasons, I guess. At the center of the lineup are Tiemoue Bakayoko and N’Golo Kante — two very similar players. Both are elite ball-winners, but neither is an especially adept distributor of the ball under pressure, especially Bakayoko.

So Allardyce’s plan from the start was to have his two more advanced central midfielders, Davies and Gueye, put pretty high, consistent pressure on Kante and Bakayoko while Chelsea was building out of the back. The goal was to force turnovers from these players before Chelsea could build a dangerous attack.

In some ways, the plan worked. Davies and Gueye unsettled Chelsea’s midfield pair, forced a few turnovers, and generally kept the Blues from building through that area. However, pushing two midfielders that high up the pitch created mismatches elsewhere, which Chelsea managed to exploit.

Take a look at the Chelsea heatmap from the opening 15 minutes of the match, courtesy of EvertonFC.com.

Davies and Gueye’s pressure did indeed keep Chelsea from successfully keeping the ball in the center of the midfield, but the Blues pretty easily bypassed that pressure down the left wing.

Left-back Marcos Alonso pushed forward and combined with left wing Pedro and false nine Eden Hazard, creating 3-v-2 situations against Aaron Lennon and Jonjoe Kenny on the Everton right. With Schneiderlin playing as a lone holding midfielder, he was not able to provide a ton of assistance in those wide areas.

The result was a bevy of Chelsea chances in the opening 15 minutes, before Allardyce decided enough was enough and instructed Davies and Gueye to sit deeper — building a block of five in front of the defensive block of four and challenging Chelsea to break his team down.

Compare the heatmap above from the first 15 minutes of the match to the Chelsea heatmap from the remainder of the first half.

The Toffees conceded the center of midfield, but made it more difficult for Chelsea to break them down in the final third — the sort of tactics you’d have expected from the opening whistle.

The second half brought more defensive changes from Allardyce, who used the following setup after Idrissa Gueye departed due to injury.

Big Sam went to five at the back, with Sandro joining Calvert-Lewin up top. DCL was quite effective in the left side of attack all match, winning countless aerial duels against the smaller Cesar Azpilicueta.

The second half played out basically as you’d have expected from there — Everton defended deep in numbers, then tried to use Calvert-Lewin’s strength and Sandro’s speed as an outlet over the top. Ashley Williams continued his resurgence alongside the effective Keane and Jagielka, while Beni Baningime continued to prove he’s ready for regular action with the senior team.

In the end, a 0-0 draw was a good result for Everton, and one the Toffees earned primarily through their deep-lying, grit-infused defending.

But, the opening quarter of an hour was also an indication that Sam Allardyce is willing to play a more aggressive style of football against top teams if he thinks there is a matchup he can exploit — and that he knows when aggression isn’t working.