Valentino Rossi finished a MotoGP race for the first time since Le Mans in mid-May.

That was the good news.

The bad news was that the glimmer of hope after 'feeling good and being fast' on his Yamaha at Assen, before crashing out, evaporated at the Sachsenring.

The Italian heads for the summer break perplexed at losing 20-seconds compared to his own race time of last season, causing him to sink from second (+2.196s) in the 2018 German Grand Prix to eighth (+19.110s) on Sunday.

Track conditions and tyres were a factor but, for comparison, Honda's race winner Marc Marquez was only three-seconds slower than last year with Rossi's team-mate and runner-up Maverick Vinales five-seconds slower.

"Today I finished, but it was a very difficult race because I was never strong enough," began Rossi, who had three DNFs in a row prior to Germany.

"For us this weekend was important because in the Assen race, before the mistake, I felt good with the bike and I was fast.

"So we had to confirm here in the Sachsenring if we had found a good way. But unfortunately, during practice sometimes I had quite good pace, but anyway I was not fast enough."

Adding to Rossi's concern is that he claimed four podiums from Le Mans to Sachsenring last season, yet hasn't done better than a fifth place in those events this season.

"We continue to suffer and we need to understand why. Because last year, these five races were the better part of my season, I was always very competitive and did some podiums, but always good races," he said.

"This year, especially in the last four races, we suffer very very much. So we need to analyse the data and understand why, because I don't feel good with the bike and I am a lot slower than last year.

"Today I was 20 seconds slower than my race time last year. This is very difficult to understand; we need to find a way. We need to find our bike."

Inevitably, when results are bad and team-mate Vinales is on the podium, Rossi faces questions about his age.

The 40-year-old insisted that, with his motivation and commitment as high as ever, there is no way that riding performance alone can account for such a big loss of race time.

"If today I was as fast as last year, but I only arrived eighth because the other guys made a step and were 20 seconds faster than last year, you say ‘maybe it's over, it's difficult’," Rossi said.

"But I'm 20 seconds slower than my own time last year. Not five years ago. And I feel good. I feel concentrated. I feel motivated. But I don't have the touch with the bike."

A notable difference between the team-mates was that while Vinales used the hard rear tyre in the race, Rossi said he had no choice but to opt for the medium (also chosen by Marquez).

"Unfortunately we start with the medium, which we knew was a little bit slower but we expected to be more constant, especially because from Michelin’s side and from our calculations, it looks like the hard won't arrive at the end," Rossi said.

"So we have tried the medium, but unfortunately the medium doesn't have grip from the beginning and anyway at the end I was in a lot of trouble."

However, Rossi insisted: "Apart from the tyre, I think that we have some other the problem because I'm not able to be strong, to ride the bike as well as I did last year."

If not the tyre then maybe the gap to Vinales - who took Yamaha's first win of the season at Assen, before being second to Marquez in Germany - is down to some small visible differences in their respective frames.

Rossi said it's possible, but added that he had also tried some modifications, only to return to the standard frame.

"Sincerely, I know what I have and we tried some different options during the season, but I remain with my chassis from the beginning of the season," explained the nine-time world champion. "But I don't know what Maverick has, so maybe he has a small different chassis. But you have to speak with him or Yamaha."

But the most likely clue as to why Vinales and rookie Fabio Quartararo have been so much stronger than their respective team-mates Rossi and Franco Morbidelli (ninth at Sachsenring) recently is to do with the type of set-up needed for the latest M1.

"It looks like the bike needs a different setting compared to last year. But looks like for me and also for Franco it's more difficult to use this type of setting, that is more where Maverick and Quartararo are very strong," Rossi explained.

"So, we need to try to understand and now we have the summer break that is good for recharging the batteries for the second half of the season. And we'll see…"

Vinales has now moved ahead of Rossi for fifth place in the world championship, as the top Yamaha rider.

The Spaniard has three podiums so far this season, with Rossi claiming two rostrums in the opening three rounds.