Before the 2015 Formula One season began, which driver pairing would you have picked as the least-evenly matched?

Romain Grosjean and Pastor Maldonado at Lotus may have got a look in, as might Daniel Ricciardo and Daniil Kvyat at Red Bull. Perhaps this would be the year Valtteri Bottas would crack on and truly dominate Felipe Massa—or maybe, given their contrasting junior records, Roberto Merhi over Will Stevens might have been a smart choice.

Four races in, some drivers are doing as many expected they would and are putting their team-mates firmly in the shade.

Others aren't quite living up to their hype—and one duo in particular, so close all the way to the end of 2014, have had very different seasons to date.

Here, we compare each team's drivers in nine different areas to see who has stamped his authority—and who is struggling to keep up.

Will Stevens Is Beating Roberto Merhi

The two Manor drivers have made just five starts between them and have only raced together twice.

Will Stevens has come out ahead on both occasions, outqualifying Roberto Merhi by a distance and also finishing the races a long way ahead.

Merhi is currently ranked ahead in the championship but has usually been behind Stevens on the track. For whatever reason, the Spaniard hasn't gotten hooked up with the car yet, and his lack of speed is surely down to more than just a weight disadvantage.

By contrast, Stevens is making an impressive-looking start to his first full season in F1. It'll be interesting to see what both can do when the new Manor is ready.

Fernando Alonso and Jenson Button Are Broadly Equal

The two McLaren drivers have each missed one race. Fernando Alonso was absent in Australia following his crash in winter testing, while Jenson Button failed to qualify for or start the Bahrain Grand Prix due to issues with his car.

Button appears to have the tiniest of edges over a single lap, but on the two occasions both have started, Alonso has been ahead at the end of the opening lap.

Both men have finished twice and each has come within a single position of scoring a point—Button in Australia and Alonso in Bahrain.

Alonso's drive in that race was the best we've seen from a McLaren so far, but to get a true handle on who has the advantage, they need to spend a bit more time together on the track.

Sergio Perez and Nico Hulkenberg Appear Equal

Force India are among the teams to have scored fewer points in 2015 than they did last season, but it's not through any fault of the drivers. The current car, far from being the finished VJM08, isn't quite good enough at the moment.

Nico Hulkenberg is doing marginally better in qualifying, having beaten team-mate Sergio Perez three times so far.

Perez has reversed the qualifying trend in the races, finishing ahead of Hulkenberg twice. The second time he did it was with a brilliant, tyre-nursing drive to eighth in the Bahrain Grand Prix.

But Hulkenberg has more points and a higher top finishing position. Neither has stamped his authority over the other at this stage, and all is to play for as they head into the European season.

Max Verstappen Looks a Little Bit Ahead of Carlos Sainz Jr.

Toro Rosso's decision to field two rookies has thus far appeared to be a good one. Both Max Verstappen and Carlos Sainz Jr. look entirely at home on the F1 grid.

Comparing the two is difficult because of Toro Rosso's poor reliability. The team have only managed one double finish—though Verstappen was classified in China, he didn't see the chequered flag.

Over a single lap they have looked evenly matched, but on the balance of the whole season, Verstappen has been more impressive. The Dutchman has lost at least one certain points-finish through reliability issues and is already making a mark with his overtaking.

But credit is also due to Sainz, who has been performing at a far higher level than many expected. We can expect good things from both as the season goes on.

Romain Grosjean Is Beating Pastor Maldonado

Lotus have encountered more misfortune than most teams in the four races to date, most of it befalling Pastor Maldonado.

But even without Maldonado's numerous problems, Romain Grosjean would be ahead in this battle. The Frenchman is one of only four drivers with a 100 percent record of outqualifying his team-mate.

Grosjean also leads the way when it comes to points, with 12 on the board compared to Maldonado's zero.

It hasn't been quite as one-sided as the figures suggest, but the Venezuelan needs to start doing more over a single lap to set himself up for better, safer race runs.

Felipe Nasr Is Beating Marcus Ericsson

Sauber's choice of Felipe Nasr looks to be bearing fruit; second-year Marcus Ericsson isn't doing too badly either.

Nasr has the edge over a single lap, outqualifying Ericsson 3-1. His advantage has been maintained over a race distance—the brilliant fifth place in Australia the highlight of a promising start to his F1 career.

Ericsson didn't impress many fans with his displays at Caterham in 2014, but though Nasr looks ahead, the Swede hasn't done a lot wrong. The silly spin on the second lap of the Malaysian Grand Prix is all that stands out.

But he is currently being put in the shade by his rookie team-mate.

Daniel Ricciardo Is Beating Daniil Kvyat

Red Bull have slipped back from where they ended 2014 and find themselves fourth in the championship with 34 fewer points than at this stage last year.

Daniel Ricciardo has at least kept one thing constant—he's beating his team-mate. The Australian has outqualified Daniil Kvyat 4-0; furthermore, he has somehow gotten his unreliable RB11 to the end of every race.

Kvyat has encountered more reliability issues and did at least finish ahead of Ricciardo on one occasion, but his single-lap pace has not been good, and he has but a single Q3 appearance to his name.

Maybe he's "got Mark Webber's car." But more likely he's just having more bad luck. Still, Ricciardo is making the Russian look relatively ordinary, and Kvyat needs to turn things around sooner rather than later.

Valtteri Bottas and Felipe Massa Are Evenly Matched

Williams have retained their place close to the front of the grid, but they don't appear likely to challenge for wins in 2015.

Valtteri Bottas and Felipe Massa may even struggle to get onto the podium. Neither has been there yet so far, each with a best finishing position of fourth.

Surprisingly, Massa has appeared to have the edge over a single lap. This was an area in which Bottas dominated in 2014, beating the Brazilian 13-6.

But Bottas has finished ahead twice to Massa's once—including in Malaysia, where he overtook his team-mate on the penultimate lap.

With just a single point between them, the Williams pair are evenly balanced at this stage with little to choose between them.

Sebastian Vettel Is Beating Kimi Raikkonen

Ferrari made a massive jump in performance over the winter and their challenge in 2015 is being led by new signing Sebastian Vettel.

The German won in Malaysia to end Ferrari's 34-race winless streak. His race driving has been coupled with excellent qualifying form which has seen him outqualify team-mate Kimi Raikkonen at every single race.

Raikkonen has not been embarrassed, and the fight has certainly not been as one-sided as the stats suggest. His sole problem is putting his SF15-T in a reasonable starting place on the grid—when the lights go out on Sunday he looks a very close match for Vettel.

But poor Saturday showings will always compromise the rest of a race weekend.

It's likely Ferrari will win again in 2015, especially if they do a good job with their power unit upgrades. When it happens, it could be either man on the top step—but on the evidence of what we've seen so far, it's more likely to be Vettel.

Lewis Hamilton Is Beating Nico Rosberg

Mercedes are again the team the beat in 2015, but the driver pairing which had such a tight battle for last season's title now appear worlds apart.

Lewis Hamilton has set the fastest time in every qualifying session so far, putting last season's pole position trophy winner Nico Rosberg firmly in the shade.

The defending champion has demonstrated a clear advantage over a race distance as well. Only in Malaysia did Rosberg look like he might have had equal pace; in the other races it has been all too easy for Hamilton.

The 27-point gap between the duo accurately reflects the season so far.

Statistical information throughout sourced from the official F1 website, the FIA, F1Fanatic's statistics database and the writer's mathematical skills.