The Irishman, who has placed inside the top 10 several times, and has won two stages at the Tour during his career, was never truly in contention this year, and heads to Paris in 18th place overall.
He had been as high as ninth after the 'crosswinds stage' – stage 10 from Saint Flour to Albi – but consistently lost time in both the Pyrenees and the Alps.
"It's been a bit strange, really. Obviously I came in with really excellent condition, and, for whatever reason, it just didn't happen. I think the team's got to look at why the performance wasn't there, but obviously today it was nice to finish on what was probably one of my best days of the race. We'll just go forward with that," he told Cyclingnews after finishing 19th on the final summit finish at Val Thorens on Saturday.
"I had the condition, but there was just something blocking me, and that's what was frustrating," he said.
When gently pressed for a more specific reason, he simply added: "I know, but I can't say. We'll look at it, and talk to the team about it, and you'll find out soon enough. We'll have talks later and figure it out going forward. As a I say, it's good to feel good on the last stage."
Martin didn't appear to be in conflict with his team at this year's race, and he even talked about heading to the Clasica San Sebastian, the Canadian WorldTour races and Il Lombardia later this season to – in his words – "do the jersey proud". Yet at the same time his comments raise questions over elements behind the scenes, which were perhaps related to nutrition.
"I came in with excellent condition, but it's just the way it is. The body emptied and I had no power in the finishes," he said. "Every day I was in the mountains and I was in the break, I was feeling good, and then suddenly the lights just went out."