"You start your career," says Hampshire's former Durham and Nottinghamshire batsman Will Smith, "hoping to just be a one-county player…. But obviously it doesn't always work out like that."

Smith is right. Increasingly, cricketers move between counties, and for reasons many and varied. Perhaps they're ambitious, or out of their depth. Need a new start, or to be closer to home. Some want more cricket and others, conversely, even move to play less, in the hope that their bodies stand up better to the rigours of a relentless season. Maybe they have no choice but to move if they wish to stay in the game, having been shown the door. They could be after a new coach, or a track better suited to their game. Perhaps, God forbid, they even leave because they want to earn more money.

That said, according to Nottinghamshire director of cricket Mick Newell: "There isn't a huge difference in the sums on offer around the country. Players don't have their wages doubled, or tripled. If the player's comfortable playing for your club it shouldn't be that difficult to retain his services or bring a new one in. It's a pretty steady scene."

Smith's two moves and James Harris' one - from Glamorgan to Middlesex - encapsulate why players go. "My first was purely opportunistic," says Smith. "I wanted to play, and Durham offered me that chance. I wanted to know if I was good enough. Durham to Hampshire was, well, having captained Durham and won Championships there, I hoped I'd end my career there. For whatever reason that opportunity wasn't afforded to me, so I had to find somewhere else. I had an inclination so I wasn't desperately surprised. There was interest from other counties but no offer, and it was a bit worrying, really. I thought I was going to have to leave the game and find something else to do. Eventually Hampshire came in and it's been great."

Harris had the world at his feet - the youngest man to take a wicket for his county at 16, a 12-fer not long after and runs too - but he had stalled at Glamorgan. Involved with England's white-ball side and with eyes on a Test call, he was carrying a heavy load in Division Two. So, with a heavy heart, he left, having not signed a contract elsewhere. He spoke to 11 counties - each trying to sell their club to him, and eventually plumped for Middlesex. It was all amicable and no money changed hands, but Harris' move was a sign of the times.

The gap between the divisions is wide. Harris knew he needed to be in Division One. One agent believes it is wider than between the Premiership and Championship, while players regularly compare moving to Division One as like leaving primary school for secondary school, citing the depth of batting, pace of bowling, quality of pitches and intensity of games. "The gap is very wide," says Smith. "It's a totally different type of cricket in Division One, where everything matters. Division Two is full of games that are hard-fought for two days and then just tail off. Everyone just wants to get out."

In the past, players have generally moved counties when their contracts were up. This winter, David Willey and Mark Footitt left Division Two with football-style fees attached to their moves, and a year each to run on their contracts. Another aspect of a transfer system that has emerged is the bonuses that counties receive for producing England players. Leicestershire receive around £100,000 per year for their role in developing Stuart Broad, and Northants can expect similar should Willey - who has moved with the express intention of playing Test cricket and being managed better - continue his upward trajectory. There's much to be gained from producing starlets, then selling them on.

Here's how a cricket transfer works.

Identifying your target
For the planet's second most played sport, top-level cricket is a small world, and there are few secrets. This is especially true in the county game, where so much cricket is played and, really, everyone knows everyone. While top football clubs post as many as 20 scouts in all corners of the globe, outside of the IPL, scouts don't exist in cricket.

In the county game, coaches and directors of cricket turn, instead, to umpires. It makes sense; as Newell says, they are readymade: "They're on the frontline, they see every player in the county game in all formats up close and personal and tend to know a bit about them as people too. Most of them have played first-class cricket themselves." Most counties will have particular umpires they will turn to for advice.

Identification of talent is based largely on experience. Newell, for instance, says he signed Harry Gurney from Leicestershire because he had never seen him bowl badly against Notts. Will Gidman, on the other hand, had not come up against Nottinghamshire but had a fine record for Gloucestershire, so Newell asked friends and umpires for their opinion and offered him a deal - one of the most lucrative on the circuit. That said, it can be impulsive: one ton or five-wicket haul and numbers can be exchanged, while there's often a pleasant clubbyness about it all, with players recommending friends and former teammates to their clubs. Look at Gloucestershire, who signed a pair of Michael Klinger's Western Australia and Perth Scorchers teammates for this season, Andrew Tye and Cameron Bancroft.

How to bag yourself an overseas deal
It is in the hiring of overseas players and Kolpak or British-passport players that agents truly come into their own. The rise of T20 has seen the overseas market change: "When I started out 10-15 years ago," says Darren Long of Beswick Sports, who moved Mark Footitt from Derbyshire to Surrey, "there were 36 overseas slots in county cricket and they were the most sought-after in the game." Now, with national teams more powerful and T20 commitments all around the world, players squeeze in stints in England and it's increasingly a balancing act. "It's all on TV now," says Beswick, "There are few secrets in the game, so there are very rarely massive surprise packages appearing and everyone knows how it works."

Newell says this is the purpose of an agent. "You'll have a few who you know well and deal with often, and you let them know what you are after and ask what is on the wires. Sometimes it's the other way round and they will come to you, especially offering Kolpak talent. You go through the dates and the small details as it can be quite difficult." Overseas recruitment can also be led by senior players who have played globally and built up contacts; in 2015, Luke Wright set up the moves for Mahela Jayawardene to Sussex.

With overseas signings, personality is taken into account less because the player simply is not around long. If a player is problematic in the dressing room, their talents are generally worth it, because they are gone in six weeks. Likewise, more deals fall through late, either as the player is withdrawn, or just a little flaky: one agent tells of an overseas star who withdrew at late notice because an opportunity to get a hair transplant had arisen.

The other way: how about a loan?
Over the last couple of seasons, county cricket has seen a few highly successful loan moves; Liam Dawson's switch to Essex sparked a run of form that earned him a national call, while Craig Meschede made his move to Glamorgan permanent. The PCA are keen on loans - especially from Division One to Two, as they safeguard against talented players carrying drinks. Often, as in the case of Middlesex's Harry Podmore's loan to Glamorgan, the parent club will tie an exciting prospect to a new contract before loaning them out, to allay fears that they will build relationships at the new county and move permanently. The more talent migrates to Division One, the more we will see loans back to Division Two: both Nottinghamshire and Warwickshire were touting around batsmen with more than five first-class centuries before this season.

Players can move on loan at any time, for as many formats as necessary (Greg Smith rejoined Leicestershire on loan last summer, just for Championship cricket), as long as the clubs see fit, and there are no set parameters about which party is responsible for paying the loanee's salary; generally it will be divided, but there is no hard and fast rule on the share.

What the future holds
Perhaps, one day, the system will be truly formalised, as in football. But for now, it is more, more, more. The vulnerable targets - Ben Duckett, Craig Miles, Olly Stone, Daniel Bell-Drummond - at smaller clubs will be poached, as the yawning divide between the divisions widens. Their current clubs will claim fees and, if and when they play for England, more money still. There will be more stockpiling of talent by wealthier clubs. More loans. More transfer fees. More relegation release clauses in contracts. More Division Two clauses in contracts. More tapping up. More money. More transfers.

This article first appeared in All Out Cricket. Click here to find out more about the magazine, available in print or digital form.

Will Macpherson writes on cricket for the Guardian, ESPNcricinfo and All Out Cricket. @willis_macp