Last summer, after a disastrous title defence, most Chelsea supporters would have thought it unlikely that their team would be soaring away at the top of the table the following February. Had they been told the Blues would be doing exactly that with a previously unheralded former Bolton and Sunderland defender in their ranks, most would probably have laughed.
Marcos Alonso's installation in the team, however, has neatly coincided with Chelsea's reversal of fortunes. Ever since making his league debut for the club in September's 3-0 defeat at Arsenal, the player signed just before the summer transfer window closed and one initially seen as a squad member has become a permanent fixture in Antonio Conte's first choice starting XI. That day he replaced Cesc Fabregas after 54 minutes as Conte switched to a back three for the first time since being appointed manager and the rest is history.
With Alonso playing left wing-back, the new system did not concede a goal in the league from that moment until seven games later. Alonso himself -- if you ignore the final result at the Emirates as his introduction came after the goals were scored -- did not taste defeat until Tottenham prevailed 2-0 on Jan.4. And he has not repeated that experience since. Apart from the last quarter of that loss at White Hart Lane as Chelsea changed personnel in trying to chase the game, he has also played every single minute of Premier League action since his debut.
Alonso has established himself as something of a lucky charm though it is also fair to say there have been some reasonable doubts over his ability to play regularly at such a high level. The defensive side of his game has been the primary area of concern with several instances of him failing to anticipate danger and not using the right body shape to cope with certain situations. When Chelsea travelled to Manchester City in early December, his defensive frailties were continually exposed by Jesus Navas, a player possessing lightning speed but little magic in his boots. Time and again the winger got in behind him and it was only poor finishing from City that saw Alonso get away with it as Chelsea ran out 3-1 winners.
The defeat at Spurs can also be partly laid at his door. Both the crosses from which Dele Alli scored were supplied from identical positions by Christian Eriksen in Alonso's area of responsibility with the wing-back failing to close down the Danish creator. In mitigation, left centre-back Gary Cahill was also equally culpable in at least one of those instances. It could also be said any defensive error from Alonso is partially magnified due to Cahill's lack of pace. Any misjudgement from Victor Moses on the other flank, for instance, is often compensated by the rapid response of Cesar Azpilicueta at right centre-back.
Alonso has clearly been working on his defending, however, as it has improved vastly since the Spurs defeat. In the 1-1 draw at Liverpool he held his position well in a counterattacking system while he was only really troubled in the 3-1 win over Arsenal on a single occasion by Theo Walcott.
At the other end of the pitch there have been far fewer reasons to worry with his ability on the ball and willingness to supplement the attack at any given opportunity proving invaluable. Alonso's crossing is generally excellent and he is happy to both whip the ball in early or overlap Eden Hazard in front of him and get down to the byline.
There have also been four well-taken goals. Alonso slotted home the second in the 5-0 rout of Everton just seconds after Hazard's opener to assert Chelsea's authority. His brace at Leicester was both more surprising and more important given they were the first two goals of the game. Indeed, he was inches away from scoring a stunning hat trick after seeing a sweetly struck volley fly just wide during the 3-0 win. More impressive still, even if it was just a header from close range, was his goal against Arsenal that put Chelsea 1-0 up and on the path to an impressive victory against a title rival.
Like the team as a whole, Alonso has been little short of a revelation this season. Whether he can sustain his form and even surpass it next campaign with the added challenges of the Champions League remain to be seen.
With a larger squad required to fight on multiple fronts, further options at wing-back are sure to be sought. Since joining Chelsea, however, Alonso has continually confounded the sceptics. At 26 and entering the prime of his career, who's to say he won't continue to do so in the months and years ahead?