Mercedes were terrible in races. They took an illegal tyre test, took a big risk, got involved in scandal and hey presto, 3 races on, they have race-winning pace. Last year, the moment they were made aware that Hamilton was listening to offers, they made an offer. McLaren were not happy, but then Merc are not playing happy families.
lol, a blind test that most people realised in the young drivers test due to the restrictions on the car was almost completely useless..... turned around the ENTIRE car design of the past 3 years in a couple of weeks. LOL. You do realise that because they couldn't test parts, or compare parts, they learnt nothing and had no idea what the tyres were making it aside from Hamilton having more time in car with new wheel, settings and more practice, almost useless as a "test".
I find it funny that you think Merc have gained, where this was the race after the full on 3 day test they weren't allowed to go to, WITH tyre test, but Merc gained through a test with blind tyres and no comparison parts, sure.
The very basis of testing is doing one run with one part, and known tyre/fuel loads and then doing the same run with a different part to compare the feel/balance/speed of the car, Merc were not able to do that, PIrelli had a test, Hamilton got some time in the car, end of.
Their race pace HASN'T been terrible, their tyre wear at some tracks has been shocking, and others brilliant... this was said by super intelligent people at the time of the worst race.... wonder who that was.
Barca is the wrong style of track AND has horrible surface that destroys tyres, everyone had tyre issues, Merc were hit the worst. Every pundit, current driver, ex driver, commentator said the same thing. Barca would not be repeated as its the known worst track for tyres on the calendar, Monaco pretty much the best. The last race Merc had huge help from Mclaren and the heat which roasted everyones tyres, which hurt Merc, but hurt other cars more, more to the point Vettel had to back off from Hamilton, from Button and from Kimi because his car was overheating. Again the great equaliser was the heat.
Barca's problem WASN'T heat, but people decided that Merc should suck at every hot race because Barcelona can be hot, the problem was the combination of heat, tyre surface and generally poor track for the car anyway. Even with better tyre wear and arctic weather the track is just one that car wouldn't be fast at.
The car improved significantly after a couple races(without a tyre test... shocking) and has been very fast since then in quali AND decent in race, but it was just the part of the season that had the worst races in terms of heat/track surface/track style for them. Other tracks were always going to be less bad but also worse for other cars. Look at Lotus, zero tyre problems, the best wear on the grid and from one race to another on different style of tracks the car looks horrendous or amazing. That has been the case for most teams every season, a car will shine some places and suck at others.