However, it was extended to 40 in a pulsating contest at the KCOM Stadium, Lazar Markovic's first Hull goal and an Oumar Niasse strike turning the game on its head.
Middlesbrough looked to respond with the pace of Traore causing problems and Eldin Jakupovic had to be alert when the 'Boro man crossed for Negredo, who saw his first time effort saved by the keeper.
And with Boro conceding four goals which puts them seven points off Premier League safety, Agnew admits his team were defensively susceptible.
And that is what they did, claiming the three points and climbed out of the relegation places.
Against the odds the match began with a bang as goal-shy Middlesbrough stunned the hosts by taking the lead through leading scorer Alvaro Negredo, who slotted home Adama Traore's low cross.
The fun and games started nearly straight away, Oumar Niasse putting the ball in the visitors' net inside three minutes only to be rightly ruled offside.
Hull would take the lead in the 27th minute as Niasse stroked the ball past the static Valdes.
It was proper end-to-end stuff and Middlesbrough were nearly back within a goal when Rudy Gestede got up high to meet a deep cross and saw his header tipped onto the crossbar by Jakupovic.
CHP talks distracted driving dangers with local high school students
"We've got to watch out for workers and we've got to be paying attention to the main thing which is driving", Franco said. April is National Distracted Driving Awareness month and it's aim is eliminating distractions behind the wheel.
The visitors did get one back in controversial circumstances in time added-on at the end of the first-half.
But Jakupovic did nothing as De Roon gave Boro a lifeline in first-half stoppage time, the goalkeeper appealing for a flag that never came as the Dutchman bundled home from Gibson's header from an offside position, referee Michael Oliver still awarding the goal even after a discussion with his linesman.
After the electric first half, the second half would prove to be much less eventful, with the key event early on being an injury to Abel Hernandez.
Nobody picked up Maguire at the far post, allowing him to power Robertson's deep free-kick delivery across goal and in with a stunning header.
After the Tigers got their fourth goal, they sought to slow the game down to ensure their victory. A free kick from left was beautifully delivered to the far post by Robertson and Maguire produced a wonderful header back across Valdes and into the far corner of the net.
Arsenal have 54 points from 29 games, while West Ham, who suffered a fifth straight loss, are 15th with 33 from 31.
Attendance: 20,380 (2,544 Visiting Supporters).