If free cash flow per share is consistently a lot lower than EPS, this is a warning sign.

 The 2 main reasons for FCF being lower than a company's EPS are:

1.  Poor operating cash conversion

2.  High levels of investment in new assets.

Poor operating cash conversion

This tends to occur when a company is growing quickly and sells a lot of its goods and services on credit.

The profits on these sales get booked in the income statement but there are no cash flows until the customer pays.

Companies may also build up stocks or inventories in anticipation of selling more.  This is fine as long as the reason is genuine.

But building up stocks is also a good way for companies to shift overhead costs such as labour away from the income statement in order to boost profits.  This can happen when companies include the overhead costs of producing stock in the balance sheet value.  If the stock is unsold at the year-end that overhead cost has not been expensed through the income statement and can therefore boost profits.  

Selling products on credit can be a sign of overtrading, or even fictitious sales.  This sort of thing never turns out well for shareholders, so you need to watch out for this.

2.  High level of investment in new assets

This is when capex is much higher than depreciation.

Depreciation reduces profits, but money spent on capex reduces free cash flow.

In this case, free cash flow per share will be a lot less than EPS.

• Capex that is consistently higher than depreciation with improvement in ROCE

It is not necessarily a problem for a company to spend heavily on capex, as long as the capex is earnings a decent ROCE.  

[Example:   Easyjet in 2015.  Its FCF per share was less than its EPS due to capex being significantly more than depreciation.  However, this is not a cause for worrying too much, as the company's ROCE had been increasing at the same time.]

• Capex that is consistently higher than depreciation with NO improvement in ROCE

However, capex that is consistently much higher than depreciation with no improvement in ROCE is rarely the hallmark of a great company.  

It can be a sign of dodgy accounting as companies can and do shift expenses into capex to boost profit.

When FCF per share is a lot less than EPS it may also be a sign that a company is manipulating its profits to make them look bigger than they really are.  

In these cases, capex is often much higher than depreciation but the company might be spending this cash just to maintain its existing assets, rather than using the expenditure to enhance it s income-producing assets.

• In a nutshell, the cash spent should be expensed against revenues and so it should reduce profits.  
• Unless it does, this, the depreciation charge reported by the company is probably too low and profits too high.