The former Liverpool midfielder entered the fray with 12 minutes remaining but was unable to turn a disappointing point into a hard-fought three.
There had been no suggestion prior to the Magpies' trip to St Andrews' that their talismanic midfielder would miss out. Afterwards, Benítez explained that Shelvey had asked not to start due to illness.
The Spaniard told the Newcastle Evening Chronicle: “Jonjo had a high fever yesterday and the doctor told me this morning he wasn’t too sure whether he could start.
“I decided it would be better to try to manage the game with fresher legs and players who had trained, and then with him it was a case of maybe trying to change something by playing him in the last 15 minutes.”
Shelvey's former boss at Liverpool, Brendan Rodgers, was also a big fan of the midfielder. During one of the first episodes of the fly-on-the-wall documentary Being: Liverpool he told Shelvey he saw him playing number 10 for a decade at Anfield.
“I’m going to put you in the number 10 tomorrow,” Rodgers said. “Because what I’m trying to do, I want to get you in the team, a regular.
“I know you’ve got all the tools to play for me for the next 10 years, do you know what I mean? So I just want you to get that in your mind, cause I’m doing it for a purpose, because when I see you, I think if I can have Joe [Allen], Lucas, you in there then that gives me three midfield players, but one that can get goals, 'cause I know you can score, 'cause you’ve got quality.”
That responsibility came too soon for the six-cap England international but he has quickly become Newcastle's key man.
Shelvey: the missing link
There can be no denying Shelvey's importance to Newcastle United this season. While Dwight Gayle's goals take the headlines, Shelvey's influence from the number 10 position has been an enormous factor in the Magpies' success so far.
Shelvey has started 31 of the Magpies' 38 Championship fixtures and missed just four in all. The four he missed, due to suspension, saw Benítez's men suffer two defeats in four games. In the three games he has come off the bench, including the draw at Birmingham City prior to the international break, Newcastle have only won once.
With 65 chances created, according to Opta, Shelvey is the second-most creative player in the Newcastle squad behind Matt Ritchie (74). The player who has created the next most chances after Shelvey is Pérez with just 34.
On top of that the 25-year-old has provided eight assists this season – the second-most for Newcastle and the fifth-highest in the Championship. He has also provided 65 through passes, the fourth-most in the league.
So what do those statistics actually mean?
They mean Shelvey is the link between the midfield and Gayle in Benítez's preferred 4-4-1-1 system. He is the one that Newcastle play through and when he is not there they do not function as effectively.
Below, Shelvey (circled) drives the Magpies forward in January's 4-0 win over Rotherham United at St James' Park. The wrong ball would slow down the counter-attack but Shelvey picks an intelligent pass and finds the run of Matt Ritchie who goes on to score.
In the next example, Shelvey breaks into the Birmingham City penalty area from the right and looks up to cut the ball back for the lurking Gayle (red circle).
This time, against Brentford at St James', Shelvey attacks the penalty area before sliding a perfectly-weighted ball into the near post for Gayle to prod home.
On top of that, players know the vision and technical ability he possesses. In the recent win over title rivals Brighton & Hove Albion, Shelvey sees Yoan Gouffran ahead of him. Ignoring simple passes (red circles) he finds the run of the French forward ahead of him.
In the still below, Shelvey again demonstrates his vision to pick out the run of Ritchie (red circle) ahead of him and exploit a gaping hole in the Rams' back four.
The alternative options
It was Pérez who started at number 10 against the Blues in Newcastle's last fixture before the international break. With five goals and as many assists in just 17 appearances in that role, the Spaniard has a record to rival Shelvey's.
So why doesn't it work as well?
Pérez and Shelvey are different players. For a start, Pérez is a striker turned into a number 10.
Shelvey's biggest strength is his ability to keep the ball moving quickly and exploit space with his range of passing and vision. Pérez, on the other hand, prefers to carry the ball himself by dribbling and that is where moves break down.
In his 29 appearances Pérez has attempted 147 dribbles at a rate of 6.1 per 90 minutes. Shelvey, who has made 34 league appearances, has tried just 76 dribbles – two per 90 minutes.
The players' respective heat maps back this up, too, with Pérez attempting most of his dribbles down the flanks – particularly the left – while Shelvey works in central areas and dribbles very infrequently.
The other player who has frequently played in the number 10 role for Benétez's side this season is Mo Diamé. The Senegalese, as the graphic above highlights, does not come out favourably when compared with Shelvey and Pérez, finishing with the fewest goals and assists – though he has attempted the most dribbles (191).
Diamé is not a natural number 10, though. His game is more about power and energy in the centre of midfield; winning the ball before giving it to creators such as Shelvey or Pérez.
Regardless of whether or not Newcastle win promotion this season, a reliable alternative to Shelvey will be near the top of Benítez's wishlist. The trouble is that players of that ilk are in high demand and short supply.
One such player might be Fulham skipper Tom Cairney. The former Blackburn Rovers playmaker has enjoyed an outstanding season for Slaviša Jokanović's Whites, bagging nine goals and assists for the west Londoners.
On top of that, he has made more passes (2,985) than Shelvey, created more opportunities (74), is only eight passes (30) behind Shelvey and has made 30 more through passes (58) than the Newcastle man this season.
Another option already lies within the ranks at St James' Park: Matt Ritchie. The former Bournemouth midfielder has been used on the right-hand side of midfield this term but has the creative statistics and qualities to rival Shelvey.
He has managed 13 goals to Shelvey's four, supplied 10 assists to Shelvey's eight and also leads in opportunities created (63). If he can manage that from a wide position then employed through the middle he could thrive.
Newcastle have an issue to resolve but could have just the tool already.