Marco Silva has seemed like a man who can do no wrong in recent weeks. If he wanted to walk down the Grand Union Canal, he could do it. If he wanted to turn water into wine, sure. Beating Arsenal? Just another day at the office.

Saturday's defeat at Chelsea was a useful reminder that the Portuguese tactician is more like you and I than we thought, although still probably a lot better at managing a Premier League football team. He makes mistakes, and for the purposes of this editorial, one in particular sticks out.

Silva is not afraid of a bit of tactical tinkering - a 5-4-1 at Swansea here, a 3-4-3 against Arsenal there - and so far, it's worked.

But you could almost hear the heads being scratched as Troy Deeney wrapped his captain's armband around Ben Watson with 10 minutes to go on the Stamford Bridge touchline, and in doing so handing the momentum straight to the Premier League champions.

Watford had been in command of the second half, scoring and missing a handful of chances and keeping their resolve despite Michy Batshuayi's equaliser 10 minutes before the substitution.

But having gained so much ground on the Blues, and restricting the game to within the final third for large swathes of the second half, the impetus gushed Chelsea's way after Watford withdrew their only recognised striker.

Any recrimination is only a mark of how far Watford have come this season, but Silva more than anyone is not a man to rest on his laurels. Where we have been so impressed by his Hornets reign so far, it is only fair to be honest when things fall short.

His substitution put Andre Carrillo and Richarlison up front, sort of, but the formation was messy and Watson lacked any clear role.

He didn't help matters by missing a challenge on Willian in the build up to Cesar Azpilicueta's winner, and giving the ball away under little pressure in the build-up to Batshuayi's fourth.

Silva spoke about the ambition of the club in pushing for a winner against Arsenal last weekend, but he could not have made his contentment with a point any clearer than with that substitution.

Phil Neville's assessment on Match of the Day was spot on. "The game changed because of the substitution,"  he said. "They sat back and allowed Chelsea to get control of the game.

"Chelsea started to dictate play, because Watford were playing deeper, allowing them to have possession."

Perhaps Silva will look at himself and consider that when you have fought your way into fourth spot in the Premier League, you have to play like it.

Watford needed to be ruthless and clinical, like they have been all season, but they weren't - although that's not just down to the head coach.

Richarlison dug his head coach out of arguably his other questionable decision on the tactics board earlier in the season, scoring late to give them a scarcely deserved late win at Swansea in September.

Silva keeps reminding us that the Brazilian is only 20, and he finally showed it on Saturday. Fresh from two late goals in three away games, he missed a brace of inviting chances at Stamford Bridge.

His header from Miguel Britos' cross, at 2-1, stands out because it would have put the game beyond Chelsea, who were already nervous and on the ropes.

Richarlison is only young, and will make mistakes, but they were both really, really simple chances which on another day he would have buried.

Luckily, you can be sure he will be as bushy-tailed and bright-eyed as usual next week, because that's what makes him great. He plays without fear, which is probably something you can't level at the Stoke defenders who have to stop him on Saturday.