It was announced last week the 28-year-old will depart Northants at the end of this season and head to New Road after more than three years at the County Ground.
Sadler revealed the club has been in contract talks with the player since last winter, but couldn't tie him down to a new deal.
And once Taylor, whose Northants contract expires at the end of the current campaign, was allowed to listen to offers from other clubs from the beginning of June onwards, it was Worcestershire who managed to persuade him his future lay with them.
"It is a blow," said Sadler, when asked about Taylor's impending departure.
"We have been negotiating terms with Tom since about November to be honest, and he was not in a position to sign.
"As soon as June 1 came round he had a couple of offers, and as much as we tried to to get a deal over the line, he felt his future was better somewhere else, and full respect to that.
"I have no problem with these lads being ambitious and wanting to go on to bigger and better things, and Tom was a good servant to us when he was here for three years.
"It is a blow, we have kind of nurtured him through as he had not got through a full season really before he joined us.
"We have now got him through three years, his body has matured and he has got into a position where he is ready to be a fully-fledged senior pro, and he has shown signs of that, certainly in the 50-over tournament."
Worcestershire will be Taylor's fourth professional club, having started out at Derbyshire and then moving on to Leicestershire ahead of his move to Northants at the back end of the 2020 campaign, when he was signed by former coach David Ripley.
And Sadler feels the deal being offered to the player by Worcestershire was simply one too good to turn down, and one that Northants were unable to match.
"Look, it is always a disappointment when a player decides to move on, but I think in the end he was offered a four-year deal at Worcester, and that was something we couldn't compete with so good luck to him," said Sadler, who also worked with Taylor when he was assistant coach at Leicestershire.
"Worcester have lost three or four players who have gone on to Notts and wherever else, so I think they have got a big bundle of cash to go an attack some players that will strengthen their squad, and that is how it works sometimes.
"I know that Tom was after a bit more security for his family, he has a young family now, and Worcester have offered him a deal that he felt he couldn't refuse.
"It is a shame to lose him, but it will give somebody else a chance and there is always that positive side of it, with one window closing another one opens so to speak.
"It is a shame to lose somebody in the prime of his career, but these things happen in professonal sport. The club has to move on."
Taylor has made 96 appearances across all competitions for Northants, and could yet bring up the century as despite the announcement of his departure he is expected to feature strongly in the club’s four-match run-in to their LV= Insurance County Championship campaign.
Northants, who sit rock-bottom of the Division One table, are back in action next Sunday when they start a four-day clash with Lancashire at the County Ground.