When Jonathan Trott was starting his career at Warwickshire, he used to tell journalists there was no point in trying to talk to him after he had scored a century.

"When I'm batting well," was the gist of it, "there's nothing in my head at all. I'm not thinking, I'm just batting. It's when I'm not scoring runs you should come and talk to me. That's when thoughts worm their way into my head."

Perhaps Steven Finn could empathise with such sentiments? When Finn started his career, bowling was a gloriously uncomplicated business. Good enough to make his county debut while his school friends were taking their GCSEs, he used his height and strength to hurl the ball at batsmen with unusual hostility. Half-a-dozen years later, relying mainly on natural attributes and conviction uncompromised by thoughts working their way into his head, he became the youngest man to claim 50 Test wickets for England.

Somewhere along the way, though, life became more complicated. Maybe it was the attempt to re-model his run-up, maybe it was a complication of trying to avoid running into the stumps, maybe it was an attempt to improve an economy rate that saw him fall behind the likes of Chris Tremlett and Tim Bresnan in the pecking order in England's four-man attack, but somewhere along the way, Finn's natural skills became diluted.

He was still a decent bowler. But that pace and hostility that made him special had largely gone and, as much as he tried to reinvent himself as a typical English-style seamer, that was never his unique selling point. There are dozens of decent fast-medium seamers in county cricket; there are very few tall fast bowlers capable of offering what Finn once had. Between July 2013 and July 2015, he didn't play a Test.

It looked, for a while, as if he had made a breakthrough. He bowled brilliantly, and with impressive pace, in his comeback Test at Edgbaston last year - claiming eight wickets in the match, including a haul of 6 for 79 in Australia's second innings, and being timed as quicker than Mitchell Johnson - demonstrating not just the welcome return to hostility but an new-found ability to swing the ball.

It wasn't quite a false dawn - he bowled terrifically without much fortune in South Africa - but it wasn't his new normal. It was more like a spike in an endlessly undulating display. Finn doesn't know where the pace comes from any more than Bob Dylan knew where the songs came from. When it goes missing, his response it to work harder and think more. It's not a bad attitude, but then Finn has never been criticised for a bad attitude. Maybe, like Mark Ramprakash before him, he wants it all a little too much, and the more he pushed for the absent pace, the more tense he became and the more his rhythm deserted him.

Certainly, when he is thrown the ball by Alastair Cook sometime this week, he will be urged not to dwell on thoughts about his technique. Instead he will be told to relax, enjoy himself and charge in. England have three other steady seamers who can swing the ball. They don't need another one. They need a fast bowler. A big, strong, fast bowler who can find life on docile surfaces and hurry batsmen when conditions are offering other bowlers nothing.

"I'll tell him not to worry too much about it," Cook said. "He sometimes can worry too much. He cares deeply about playing for England and doesn't want to let anyone down.

"It is hard to explain sometimes why he can bowl quicker than the other days. It's not for lack of effort, but it doesn't seem to come out quite as well. He is a rhythm bowler."

There have been, Cook believes, some physical reasons for Finn's underwhelming displays in recent times. As well as a knee injury picked up when falling in his delivery stride, he also had a damaged toenail that has now been treated. As a result, he goes into this game without any of the nagging impediments that might have otherwise preyed on his mind. He impressed in the nets on Tuesday - a display that probably tipped selection in his favour over Jake Ball - and bowled with decent pace in Middlesex's two most recent limited-overs games.

"He bowled quickly in the nets," Cook said. "And quickly for Middlesex against Essex. On his day, he bowls spells which are incredible to be standing at first slip for, as he did against Australia here. He's a huge talent.

"Sometimes when you're dropped it's a bit of a moment for you as a player. He obviously missed out on the last Test and that will have hurt him. When telling him he wasn't playing, you saw that disappointment and hunger almost straight away. And telling him he was playing today, you saw that glint in his eye."

It took a sleepless night before the team management opted for Finn over Ball - "at 2am today I was wide awake thinking about it," Cook said - but there is some logic in the decision. Not only does Finn have good memories of Edgbaston, a not insignificant factor for a man whose fortunes seem to be strongly influenced by his frame of mind, but he also offers, at his best, something a bit different to England's other bowlers. As Cook put it: "We've gone for a guy with a proven Test record who has a knack of picking up wickets."

Ball is unfortunate, though. He looks a skilful, reliable bowler who, with a bit of fitness work - it was noticeable that his speeds dropped by the spell at Lord's - could have a long-term role in this side. In the end, his similarities to Stuart Broad and James Anderson may have counted against him.

Realistically, though, he and Finn may well be competing for a spot in the touring squads to Bangladesh and India. With Mark Wood also likely to be in the mix, competition for places is tough, though there is a strong case for resting Anderson, in particular, for Bangladesh. Suffice it to say, Finn needs the Edgbaston Test to go well. Aged 27, he is getting to the stage where talk of his potential has to be replaced by talk of his achievements to sustain his career. It's not quite now or never, but he is heading in that direction.

The same might be said for James Vince. He has only had seven Test innings but it is getting to the stage where he needs a performance if he is to retain a place for The Oval Test. The impression remains that, if Ian Bell had been able to score a little more heavily in county cricket this season (he has just one Championship century to his name), he may be back already. This pitch promises, despite recent rain, to be good. Vince needs to take advantage.

George Dobell is a senior correspondent at ESPNcricinfo